diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java
index 1006963dec2..e57a967ad23 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilder.java
@@ -35,12 +35,14 @@ import oracle.ucp.jdbc.PoolDataSource;
 import oracle.ucp.jdbc.PoolDataSourceImpl;
 import org.apache.commons.dbcp2.BasicDataSource;
 import org.h2.jdbcx.JdbcDataSource;
+import org.jspecify.annotations.Nullable;
 import org.postgresql.ds.PGSimpleDataSource;
 import org.vibur.dbcp.ViburDBCPDataSource;
 
 import org.springframework.beans.BeanUtils;
 import org.springframework.core.ResolvableType;
 import org.springframework.jdbc.datasource.SimpleDriverDataSource;
+import org.springframework.lang.Contract;
 import org.springframework.util.Assert;
 import org.springframework.util.ClassUtils;
 import org.springframework.util.ReflectionUtils;
@@ -89,15 +91,15 @@ import org.springframework.util.StringUtils;
  */
 public final class DataSourceBuilder<T extends DataSource> {
 
-	private final ClassLoader classLoader;
+	private final @Nullable ClassLoader classLoader;
 
 	private final Map<DataSourceProperty, String> values = new HashMap<>();
 
-	private Class<T> type;
+	private @Nullable Class<T> type;
 
-	private final DataSource deriveFrom;
+	private final @Nullable DataSource deriveFrom;
 
-	private DataSourceBuilder(ClassLoader classLoader) {
+	private DataSourceBuilder(@Nullable ClassLoader classLoader) {
 		this.classLoader = classLoader;
 		this.deriveFrom = null;
 	}
@@ -117,7 +119,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 	 * @return this builder
 	 */
 	@SuppressWarnings("unchecked")
-	public <D extends DataSource> DataSourceBuilder<D> type(Class<D> type) {
+	public <D extends DataSource> DataSourceBuilder<D> type(@Nullable Class<D> type) {
 		this.type = (Class<T>) type;
 		return (DataSourceBuilder<D>) this;
 	}
@@ -147,7 +149,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 	 * @param username the user name
 	 * @return this builder
 	 */
-	public DataSourceBuilder<T> username(String username) {
+	public DataSourceBuilder<T> username(@Nullable String username) {
 		set(DataSourceProperty.USERNAME, username);
 		return this;
 	}
@@ -157,12 +159,12 @@ public final class DataSourceBuilder<T extends DataSource> {
 	 * @param password the password
 	 * @return this builder
 	 */
-	public DataSourceBuilder<T> password(String password) {
+	public DataSourceBuilder<T> password(@Nullable String password) {
 		set(DataSourceProperty.PASSWORD, password);
 		return this;
 	}
 
-	private void set(DataSourceProperty property, String value) {
+	private void set(DataSourceProperty property, @Nullable String value) {
 		this.values.put(property, value);
 	}
 
@@ -178,7 +180,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 		Set<DataSourceProperty> applied = new HashSet<>();
 		for (DataSourceProperty property : DataSourceProperty.values()) {
 			String value = this.values.get(property);
-			if (value == null && deriveFromProperties != null && properties.canSet(property)) {
+			if (value == null && deriveFromProperties != null && this.deriveFrom != null
+					&& properties.canSet(property)) {
 				value = deriveFromProperties.get(this.deriveFrom, property);
 			}
 			if (value != null) {
@@ -193,14 +196,14 @@ public final class DataSourceBuilder<T extends DataSource> {
 			DatabaseDriver driver = DatabaseDriver.fromJdbcUrl(url);
 			String driverClassName = driver.getDriverClassName();
 			if (driverClassName != null) {
-				properties.set(dataSource, DataSourceProperty.DRIVER_CLASS_NAME, driver.getDriverClassName());
+				properties.set(dataSource, DataSourceProperty.DRIVER_CLASS_NAME, driverClassName);
 			}
 		}
 		return dataSource;
 	}
 
 	@SuppressWarnings("unchecked")
-	private DataSourceProperties<DataSource> getDeriveFromProperties() {
+	private @Nullable DataSourceProperties<DataSource> getDeriveFromProperties() {
 		if (this.deriveFrom == null) {
 			return null;
 		}
@@ -220,7 +223,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 	 * @param classLoader the classloader used to discover preferred settings
 	 * @return a new {@link DataSource} builder instance
 	 */
-	public static DataSourceBuilder<?> create(ClassLoader classLoader) {
+	public static DataSourceBuilder<?> create(@Nullable ClassLoader classLoader) {
 		return new DataSourceBuilder<>(classLoader);
 	}
 
@@ -258,7 +261,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 	 * @param classLoader the classloader used to discover preferred settings
 	 * @return the preferred {@link DataSource} type
 	 */
-	public static Class<? extends DataSource> findType(ClassLoader classLoader) {
+	public static @Nullable Class<? extends DataSource> findType(@Nullable ClassLoader classLoader) {
 		MappedDataSourceProperties<?> mappings = MappedDataSourceProperties.forType(classLoader, null);
 		return (mappings != null) ? mappings.getDataSourceInstanceType() : null;
 	}
@@ -294,15 +297,15 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return this.names[0];
 		}
 
-		Method findSetter(Class<?> type) {
+		@Nullable Method findSetter(Class<?> type) {
 			return findMethod("set", type, String.class);
 		}
 
-		Method findGetter(Class<?> type) {
+		@Nullable Method findGetter(Class<?> type) {
 			return findMethod("get", type);
 		}
 
-		private Method findMethod(String prefix, Class<?> type, Class<?>... paramTypes) {
+		private @Nullable Method findMethod(String prefix, Class<?> type, Class<?>... paramTypes) {
 			for (String name : this.names) {
 				String candidate = prefix + StringUtils.capitalize(name);
 				Method method = ReflectionUtils.findMethod(type, candidate, paramTypes);
@@ -323,11 +326,16 @@ public final class DataSourceBuilder<T extends DataSource> {
 
 		void set(T dataSource, DataSourceProperty property, String value);
 
-		String get(T dataSource, DataSourceProperty property);
+		@Nullable String get(T dataSource, DataSourceProperty property);
 
-		static <T extends DataSource> DataSourceProperties<T> forType(ClassLoader classLoader, Class<T> type) {
+		static <T extends DataSource> DataSourceProperties<T> forType(@Nullable ClassLoader classLoader,
+				@Nullable Class<T> type) {
 			MappedDataSourceProperties<T> mapped = MappedDataSourceProperties.forType(classLoader, type);
-			return (mapped != null) ? mapped : new ReflectionDataSourceProperties<>(type);
+			if (mapped != null) {
+				return mapped;
+			}
+			Assert.state(type != null, "No supported DataSource type found");
+			return new ReflectionDataSourceProperties<>(type);
 		}
 
 	}
@@ -338,10 +346,16 @@ public final class DataSourceBuilder<T extends DataSource> {
 
 		private final Class<T> dataSourceType;
 
-		@SuppressWarnings("unchecked")
 		MappedDataSourceProperties() {
-			this.dataSourceType = (Class<T>) ResolvableType.forClass(MappedDataSourceProperties.class, getClass())
+			this.dataSourceType = getGeneric();
+		}
+
+		@SuppressWarnings("unchecked")
+		private Class<T> getGeneric() {
+			Class<T> generic = (Class<T>) ResolvableType.forClass(MappedDataSourceProperties.class, getClass())
 				.resolveGeneric();
+			Assert.state(generic != null, "'generic' must not be null");
+			return generic;
 		}
 
 		@Override
@@ -349,11 +363,12 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return this.dataSourceType;
 		}
 
-		protected void add(DataSourceProperty property, Getter<T, String> getter, Setter<T, String> setter) {
+		protected void add(DataSourceProperty property, @Nullable Getter<T, String> getter, Setter<T, String> setter) {
 			add(property, String.class, getter, setter);
 		}
 
-		protected <V> void add(DataSourceProperty property, Class<V> type, Getter<T, V> getter, Setter<T, V> setter) {
+		protected <V> void add(DataSourceProperty property, Class<V> type, @Nullable Getter<T, V> getter,
+				Setter<T, V> setter) {
 			this.mappedProperties.put(property, new MappedDataSourceProperty<>(property, type, getter, setter));
 		}
 
@@ -371,7 +386,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 		}
 
 		@Override
-		public String get(T dataSource, DataSourceProperty property) {
+		public @Nullable String get(T dataSource, DataSourceProperty property) {
 			MappedDataSourceProperty<T, ?> mappedProperty = getMapping(property);
 			if (mappedProperty != null) {
 				return mappedProperty.get(dataSource);
@@ -379,14 +394,15 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return null;
 		}
 
-		private MappedDataSourceProperty<T, ?> getMapping(DataSourceProperty property) {
+		private @Nullable MappedDataSourceProperty<T, ?> getMapping(DataSourceProperty property) {
 			MappedDataSourceProperty<T, ?> mappedProperty = this.mappedProperties.get(property);
 			UnsupportedDataSourcePropertyException.throwIf(!property.isOptional() && mappedProperty == null,
 					() -> "No mapping found for " + property);
 			return mappedProperty;
 		}
 
-		static <T extends DataSource> MappedDataSourceProperties<T> forType(ClassLoader classLoader, Class<T> type) {
+		static <T extends DataSource> @Nullable MappedDataSourceProperties<T> forType(@Nullable ClassLoader classLoader,
+				@Nullable Class<T> type) {
 			MappedDataSourceProperties<T> pooled = lookupPooled(classLoader, type);
 			if (type == null || pooled != null) {
 				return pooled;
@@ -394,8 +410,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return lookupBasic(classLoader, type);
 		}
 
-		private static <T extends DataSource> MappedDataSourceProperties<T> lookupPooled(ClassLoader classLoader,
-				Class<T> type) {
+		private static <T extends DataSource> @Nullable MappedDataSourceProperties<T> lookupPooled(
+				@Nullable ClassLoader classLoader, @Nullable Class<T> type) {
 			MappedDataSourceProperties<T> result = null;
 			result = lookup(classLoader, type, result, "com.zaxxer.hikari.HikariDataSource",
 					HikariDataSourceProperties::new);
@@ -412,8 +428,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return result;
 		}
 
-		private static <T extends DataSource> MappedDataSourceProperties<T> lookupBasic(ClassLoader classLoader,
-				Class<T> dataSourceType) {
+		private static <T extends DataSource> @Nullable MappedDataSourceProperties<T> lookupBasic(
+				@Nullable ClassLoader classLoader, Class<T> dataSourceType) {
 			MappedDataSourceProperties<T> result = null;
 			result = lookup(classLoader, dataSourceType, result,
 					"org.springframework.jdbc.datasource.SimpleDriverDataSource", SimpleDataSourceProperties::new);
@@ -427,8 +443,9 @@ public final class DataSourceBuilder<T extends DataSource> {
 		}
 
 		@SuppressWarnings("unchecked")
-		private static <T extends DataSource> MappedDataSourceProperties<T> lookup(ClassLoader classLoader,
-				Class<T> dataSourceType, MappedDataSourceProperties<T> existing, String dataSourceClassName,
+		private static <T extends DataSource> @Nullable MappedDataSourceProperties<T> lookup(
+				@Nullable ClassLoader classLoader, @Nullable Class<T> dataSourceType,
+				@Nullable MappedDataSourceProperties<T> existing, String dataSourceClassName,
 				Supplier<MappedDataSourceProperties<?>> propertyMappingsSupplier, String... requiredClassNames) {
 			if (existing != null || !allPresent(classLoader, dataSourceClassName, requiredClassNames)) {
 				return existing;
@@ -439,7 +456,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 							? (MappedDataSourceProperties<T>) propertyMappings : null;
 		}
 
-		private static boolean allPresent(ClassLoader classLoader, String dataSourceClassName,
+		private static boolean allPresent(@Nullable ClassLoader classLoader, String dataSourceClassName,
 				String[] requiredClassNames) {
 			boolean result = ClassUtils.isPresent(dataSourceClassName, classLoader);
 			for (String requiredClassName : requiredClassNames) {
@@ -456,11 +473,12 @@ public final class DataSourceBuilder<T extends DataSource> {
 
 		private final Class<V> type;
 
-		private final Getter<T, V> getter;
+		private final @Nullable Getter<T, V> getter;
 
-		private final Setter<T, V> setter;
+		private final @Nullable Setter<T, V> setter;
 
-		MappedDataSourceProperty(DataSourceProperty property, Class<V> type, Getter<T, V> getter, Setter<T, V> setter) {
+		MappedDataSourceProperty(DataSourceProperty property, Class<V> type, @Nullable Getter<T, V> getter,
+				@Nullable Setter<T, V> setter) {
 			this.property = property;
 			this.type = type;
 			this.getter = getter;
@@ -481,7 +499,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 			}
 		}
 
-		String get(T dataSource) {
+		@Nullable String get(T dataSource) {
 			try {
 				if (this.getter == null) {
 					UnsupportedDataSourcePropertyException.throwIf(!this.property.isOptional(),
@@ -506,7 +524,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 			throw new IllegalStateException("Unsupported value type " + this.type);
 		}
 
-		private String convertToString(V value) {
+		@Contract("!null -> !null")
+		private @Nullable String convertToString(@Nullable V value) {
 			if (value == null) {
 				return null;
 			}
@@ -530,7 +549,6 @@ public final class DataSourceBuilder<T extends DataSource> {
 		private final Class<T> dataSourceType;
 
 		ReflectionDataSourceProperties(Class<T> dataSourceType) {
-			Assert.state(dataSourceType != null, "No supported DataSource type found");
 			Map<DataSourceProperty, Method> getters = new HashMap<>();
 			Map<DataSourceProperty, Method> setters = new HashMap<>();
 			for (DataSourceProperty property : DataSourceProperty.values()) {
@@ -542,7 +560,8 @@ public final class DataSourceBuilder<T extends DataSource> {
 			this.setters = Collections.unmodifiableMap(setters);
 		}
 
-		private void putIfNotNull(Map<DataSourceProperty, Method> map, DataSourceProperty property, Method method) {
+		private void putIfNotNull(Map<DataSourceProperty, Method> map, DataSourceProperty property,
+				@Nullable Method method) {
 			if (method != null) {
 				map.put(property, method);
 			}
@@ -567,7 +586,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 		}
 
 		@Override
-		public String get(T dataSource, DataSourceProperty property) {
+		public @Nullable String get(T dataSource, DataSourceProperty property) {
 			Method method = getMethod(property, this.getters);
 			if (method != null) {
 				return (String) ReflectionUtils.invokeMethod(method, dataSource);
@@ -575,7 +594,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 			return null;
 		}
 
-		private Method getMethod(DataSourceProperty property, Map<DataSourceProperty, Method> methods) {
+		private @Nullable Method getMethod(DataSourceProperty property, Map<DataSourceProperty, Method> methods) {
 			Method method = methods.get(property);
 			if (method == null) {
 				UnsupportedDataSourcePropertyException.throwIf(!property.isOptional(),
@@ -591,7 +610,7 @@ public final class DataSourceBuilder<T extends DataSource> {
 	@FunctionalInterface
 	private interface Getter<T, V> {
 
-		V get(T instance) throws SQLException;
+		@Nullable V get(T instance) throws SQLException;
 
 	}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilderRuntimeHints.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilderRuntimeHints.java
index e046ee55262..68f8c8cadb6 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilderRuntimeHints.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceBuilderRuntimeHints.java
@@ -22,6 +22,8 @@ import java.util.List;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aot.hint.MemberCategory;
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -51,7 +53,7 @@ class DataSourceBuilderRuntimeHints implements RuntimeHintsRegistrar {
 	}
 
 	@Override
-	public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+	public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 		for (String typeName : TYPE_NAMES) {
 			hints.reflection()
 				.registerTypeIfPresent(classLoader, typeName,
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceUnwrapper.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceUnwrapper.java
index d08faca4ae2..af4cda88066 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceUnwrapper.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DataSourceUnwrapper.java
@@ -20,6 +20,8 @@ import java.sql.Wrapper;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.aop.framework.AopProxyUtils;
 import org.springframework.aop.support.AopUtils;
 import org.springframework.jdbc.datasource.DelegatingDataSource;
@@ -53,7 +55,8 @@ public final class DataSourceUnwrapper {
 	 * @since 2.3.8
 	 * @see Wrapper#unwrap(Class)
 	 */
-	public static <I, T extends I> T unwrap(DataSource dataSource, Class<I> unwrapInterface, Class<T> target) {
+	public static <I, T extends I> @Nullable T unwrap(DataSource dataSource, Class<I> unwrapInterface,
+			Class<T> target) {
 		if (target.isInstance(dataSource)) {
 			return target.cast(dataSource);
 		}
@@ -86,11 +89,11 @@ public final class DataSourceUnwrapper {
 	 * @param <T> the target type
 	 * @return an object that implements the target type or {@code null}
 	 */
-	public static <T> T unwrap(DataSource dataSource, Class<T> target) {
+	public static <T> @Nullable T unwrap(DataSource dataSource, Class<T> target) {
 		return unwrap(dataSource, target, target);
 	}
 
-	private static <S> S safeUnwrap(Wrapper wrapper, Class<S> target) {
+	private static <S> @Nullable S safeUnwrap(Wrapper wrapper, Class<S> target) {
 		try {
 			if (target.isInterface() && wrapper.isWrapperFor(target)) {
 				return wrapper.unwrap(target);
@@ -104,7 +107,7 @@ public final class DataSourceUnwrapper {
 
 	private static final class DelegatingDataSourceUnwrapper {
 
-		private static DataSource getTargetDataSource(DataSource dataSource) {
+		private static @Nullable DataSource getTargetDataSource(DataSource dataSource) {
 			if (dataSource instanceof DelegatingDataSource delegatingDataSource) {
 				return delegatingDataSource.getTargetDataSource();
 			}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DatabaseDriver.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DatabaseDriver.java
index 3b5303221da..0fbaeaa2cfc 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DatabaseDriver.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/DatabaseDriver.java
@@ -21,6 +21,8 @@ import java.util.Collection;
 import java.util.Collections;
 import java.util.Locale;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -233,23 +235,25 @@ public enum DatabaseDriver {
 
 	};
 
-	private final String productName;
+	private final @Nullable String productName;
 
-	private final String driverClassName;
+	private final @Nullable String driverClassName;
 
-	private final String xaDataSourceClassName;
+	private final @Nullable String xaDataSourceClassName;
 
-	private final String validationQuery;
+	private final @Nullable String validationQuery;
 
-	DatabaseDriver(String productName, String driverClassName) {
+	DatabaseDriver(@Nullable String productName, @Nullable String driverClassName) {
 		this(productName, driverClassName, null);
 	}
 
-	DatabaseDriver(String productName, String driverClassName, String xaDataSourceClassName) {
+	DatabaseDriver(@Nullable String productName, @Nullable String driverClassName,
+			@Nullable String xaDataSourceClassName) {
 		this(productName, driverClassName, xaDataSourceClassName, null);
 	}
 
-	DatabaseDriver(String productName, String driverClassName, String xaDataSourceClassName, String validationQuery) {
+	DatabaseDriver(@Nullable String productName, @Nullable String driverClassName,
+			@Nullable String xaDataSourceClassName, @Nullable String validationQuery) {
 		this.productName = productName;
 		this.driverClassName = driverClassName;
 		this.xaDataSourceClassName = xaDataSourceClassName;
@@ -280,7 +284,7 @@ public enum DatabaseDriver {
 	 * Return the driver class name.
 	 * @return the class name or {@code null}
 	 */
-	public String getDriverClassName() {
+	public @Nullable String getDriverClassName() {
 		return this.driverClassName;
 	}
 
@@ -288,7 +292,7 @@ public enum DatabaseDriver {
 	 * Return the XA driver source class name.
 	 * @return the class name or {@code null}
 	 */
-	public String getXaDataSourceClassName() {
+	public @Nullable String getXaDataSourceClassName() {
 		return this.xaDataSourceClassName;
 	}
 
@@ -296,7 +300,7 @@ public enum DatabaseDriver {
 	 * Return the validation query.
 	 * @return the validation query or {@code null}
 	 */
-	public String getValidationQuery() {
+	public @Nullable String getValidationQuery() {
 		return this.validationQuery;
 	}
 
@@ -305,7 +309,7 @@ public enum DatabaseDriver {
 	 * @param url the JDBC URL
 	 * @return the database driver or {@link #UNKNOWN} if not found
 	 */
-	public static DatabaseDriver fromJdbcUrl(String url) {
+	public static DatabaseDriver fromJdbcUrl(@Nullable String url) {
 		if (StringUtils.hasLength(url)) {
 			Assert.isTrue(url.startsWith("jdbc"), "'url' must start with \"jdbc\"");
 			String urlWithoutPrefix = url.substring("jdbc".length()).toLowerCase(Locale.ENGLISH);
@@ -326,7 +330,7 @@ public enum DatabaseDriver {
 	 * @param productName product name
 	 * @return the database driver or {@link #UNKNOWN} if not found
 	 */
-	public static DatabaseDriver fromProductName(String productName) {
+	public static DatabaseDriver fromProductName(@Nullable String productName) {
 		if (StringUtils.hasLength(productName)) {
 			for (DatabaseDriver candidate : values()) {
 				if (candidate.matchProductName(productName)) {
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/EmbeddedDatabaseConnection.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/EmbeddedDatabaseConnection.java
index 9c62a648e73..b5809c6c023 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/EmbeddedDatabaseConnection.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/EmbeddedDatabaseConnection.java
@@ -24,6 +24,8 @@ import java.util.stream.Stream;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.dao.DataAccessException;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
 import org.springframework.util.Assert;
@@ -64,15 +66,15 @@ public enum EmbeddedDatabaseConnection {
 	 */
 	HSQLDB("org.hsqldb.jdbcDriver", "jdbc:hsqldb:mem:%s");
 
-	private final String alternativeDriverClass;
+	private final @Nullable String alternativeDriverClass;
 
-	private final String url;
+	private final @Nullable String url;
 
-	EmbeddedDatabaseConnection(String url) {
+	EmbeddedDatabaseConnection(@Nullable String url) {
 		this(null, url);
 	}
 
-	EmbeddedDatabaseConnection(String fallbackDriverClass, String url) {
+	EmbeddedDatabaseConnection(@Nullable String fallbackDriverClass, @Nullable String url) {
 		this.alternativeDriverClass = fallbackDriverClass;
 		this.url = url;
 	}
@@ -81,7 +83,7 @@ public enum EmbeddedDatabaseConnection {
 	 * Returns the driver class name.
 	 * @return the driver class name
 	 */
-	public String getDriverClassName() {
+	public @Nullable String getDriverClassName() {
 		// See https://github.com/spring-projects/spring-boot/issues/32865
 		return switch (this) {
 			case NONE -> null;
@@ -95,7 +97,7 @@ public enum EmbeddedDatabaseConnection {
 	 * Returns the {@link EmbeddedDatabaseType} for the connection.
 	 * @return the database type
 	 */
-	public EmbeddedDatabaseType getType() {
+	public @Nullable EmbeddedDatabaseType getType() {
 		// See https://github.com/spring-projects/spring-boot/issues/32865
 		return switch (this) {
 			case NONE -> null;
@@ -110,7 +112,7 @@ public enum EmbeddedDatabaseConnection {
 	 * @param databaseName the name of the database
 	 * @return the connection URL
 	 */
-	public String getUrl(String databaseName) {
+	public @Nullable String getUrl(String databaseName) {
 		Assert.hasText(databaseName, "'databaseName' must not be empty");
 		return (this.url != null) ? String.format(this.url, databaseName) : null;
 	}
@@ -125,7 +127,7 @@ public enum EmbeddedDatabaseConnection {
 		};
 	}
 
-	boolean isDriverCompatible(String driverClass) {
+	boolean isDriverCompatible(@Nullable String driverClass) {
 		return (driverClass != null
 				&& (driverClass.equals(getDriverClassName()) || driverClass.equals(this.alternativeDriverClass)));
 	}
@@ -138,7 +140,7 @@ public enum EmbeddedDatabaseConnection {
 	 * @return true if the driver class and url refer to an embedded database
 	 * @since 2.4.0
 	 */
-	public static boolean isEmbedded(String driverClass, String url) {
+	public static boolean isEmbedded(@Nullable String driverClass, @Nullable String url) {
 		if (driverClass == null) {
 			return false;
 		}
@@ -178,9 +180,14 @@ public enum EmbeddedDatabaseConnection {
 	 * @param classLoader the class loader used to check for classes
 	 * @return an {@link EmbeddedDatabaseConnection} or {@link #NONE}.
 	 */
-	public static EmbeddedDatabaseConnection get(ClassLoader classLoader) {
+	public static EmbeddedDatabaseConnection get(@Nullable ClassLoader classLoader) {
 		for (EmbeddedDatabaseConnection candidate : EmbeddedDatabaseConnection.values()) {
-			if (candidate != NONE && ClassUtils.isPresent(candidate.getDriverClassName(), classLoader)) {
+			if (candidate == NONE) {
+				continue;
+			}
+			String driverClassName = candidate.getDriverClassName();
+			Assert.state(driverClassName != null, "'driverClassName' must not be null");
+			if (ClassUtils.isPresent(driverClassName, classLoader)) {
 				return candidate;
 			}
 		}
@@ -202,7 +209,12 @@ public enum EmbeddedDatabaseConnection {
 			productName = productName.toUpperCase(Locale.ENGLISH);
 			EmbeddedDatabaseConnection[] candidates = EmbeddedDatabaseConnection.values();
 			for (EmbeddedDatabaseConnection candidate : candidates) {
-				if (candidate != NONE && productName.contains(candidate.getType().name())) {
+				if (candidate == NONE) {
+					continue;
+				}
+				EmbeddedDatabaseType type = candidate.getType();
+				Assert.state(type != null, "'type' must not be null");
+				if (productName.contains(type.name())) {
 					String url = metaData.getURL();
 					return (url == null || candidate.isEmbeddedUrl(url));
 				}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/HikariCheckpointRestoreLifecycle.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/HikariCheckpointRestoreLifecycle.java
index 1fcdac1a18f..e12ee0648d1 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/HikariCheckpointRestoreLifecycle.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/HikariCheckpointRestoreLifecycle.java
@@ -33,6 +33,7 @@ import com.zaxxer.hikari.HikariPoolMXBean;
 import com.zaxxer.hikari.pool.HikariPool;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.context.ConfigurableApplicationContext;
 import org.springframework.context.Lifecycle;
@@ -71,7 +72,7 @@ public class HikariCheckpointRestoreLifecycle implements Lifecycle {
 
 	private final Function<HikariPool, Boolean> hasOpenConnections;
 
-	private final HikariDataSource dataSource;
+	private final @Nullable HikariDataSource dataSource;
 
 	private final ConfigurableApplicationContext applicationContext;
 
@@ -123,15 +124,16 @@ public class HikariCheckpointRestoreLifecycle implements Lifecycle {
 						+ "Please configure allow-pool-suspension to fix this!");
 			}
 		}
-		closeConnections(Duration.ofMillis(this.dataSource.getConnectionTimeout() + 250));
+		closeConnections(this.dataSource, Duration.ofMillis(this.dataSource.getConnectionTimeout() + 250));
 	}
 
-	private void closeConnections(Duration shutdownTimeout) {
+	private void closeConnections(HikariDataSource dataSource, Duration shutdownTimeout) {
 		logger.info("Evicting Hikari connections");
-		this.dataSource.getHikariPoolMXBean().softEvictConnections();
+		dataSource.getHikariPoolMXBean().softEvictConnections();
 		logger.debug(LogMessage.format("Waiting %d seconds for Hikari connections to be closed",
 				shutdownTimeout.toSeconds()));
-		CompletableFuture<Void> allConnectionsClosed = CompletableFuture.runAsync(this::waitForConnectionsToClose);
+		CompletableFuture<Void> allConnectionsClosed = CompletableFuture
+			.runAsync(() -> this.waitForConnectionsToClose(dataSource));
 		try {
 			allConnectionsClosed.get(shutdownTimeout.toMillis(), TimeUnit.MILLISECONDS);
 			logger.debug("Hikari connections closed");
@@ -148,8 +150,8 @@ public class HikariCheckpointRestoreLifecycle implements Lifecycle {
 		}
 	}
 
-	private void waitForConnectionsToClose() {
-		while (this.hasOpenConnections.apply((HikariPool) this.dataSource.getHikariPoolMXBean())) {
+	private void waitForConnectionsToClose(HikariDataSource dataSource) {
+		while (this.hasOpenConnections.apply((HikariPool) dataSource.getHikariPoolMXBean())) {
 			try {
 				TimeUnit.MILLISECONDS.sleep(50);
 			}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceConfiguration.java
index cd2784bf3a4..c9ce99db97e 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceConfiguration.java
@@ -23,6 +23,7 @@ import javax.sql.DataSource;
 import com.zaxxer.hikari.HikariDataSource;
 import oracle.jdbc.OracleConnection;
 import oracle.ucp.jdbc.PoolDataSourceImpl;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
@@ -49,14 +50,14 @@ import org.springframework.util.StringUtils;
 abstract class DataSourceConfiguration {
 
 	@SuppressWarnings("unchecked")
-	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails, Class<? extends DataSource> type,
-			ClassLoader classLoader) {
+	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails,
+			@Nullable Class<? extends DataSource> type, ClassLoader classLoader) {
 		return createDataSource(connectionDetails, type, classLoader, true);
 	}
 
 	@SuppressWarnings("unchecked")
-	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails, Class<? extends DataSource> type,
-			ClassLoader classLoader, boolean applyDriverClassName) {
+	private static <T> T createDataSource(JdbcConnectionDetails connectionDetails,
+			@Nullable Class<? extends DataSource> type, ClassLoader classLoader, boolean applyDriverClassName) {
 		DataSourceBuilder<? extends DataSource> builder = DataSourceBuilder.create(classLoader).type(type);
 		if (applyDriverClassName) {
 			builder.driverClassName(connectionDetails.getDriverClassName());
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceInitializationAutoConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceInitializationAutoConfiguration.java
index e0b1300bc5e..c2d4facf2c5 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceInitializationAutoConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceInitializationAutoConfiguration.java
@@ -18,6 +18,8 @@ package org.springframework.boot.jdbc.autoconfigure;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.autoconfigure.AutoConfiguration;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnClass;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnMissingBean;
@@ -57,7 +59,8 @@ public final class DataSourceInitializationAutoConfiguration {
 				determineDataSource(dataSource, properties.getUsername(), properties.getPassword()), properties);
 	}
 
-	private static DataSource determineDataSource(DataSource dataSource, String username, String password) {
+	private static DataSource determineDataSource(DataSource dataSource, @Nullable String username,
+			@Nullable String password) {
 		if (StringUtils.hasText(username) && StringUtils.hasText(password)) {
 			return DataSourceBuilder.derivedFrom(dataSource)
 				.username(username)
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceJmxConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceJmxConfiguration.java
index 53472a0e9e9..40b0949edb7 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceJmxConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceJmxConfiguration.java
@@ -26,6 +26,7 @@ import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 import org.apache.tomcat.jdbc.pool.DataSourceProxy;
 import org.apache.tomcat.jdbc.pool.PoolConfiguration;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.boot.autoconfigure.condition.ConditionalOnBooleanProperty;
@@ -81,7 +82,7 @@ class DataSourceJmxConfiguration {
 
 		@Bean
 		@ConditionalOnMissingBean(name = "dataSourceMBean")
-		Object dataSourceMBean(DataSource dataSource) {
+		@Nullable Object dataSourceMBean(DataSource dataSource) {
 			DataSourceProxy dataSourceProxy = DataSourceUnwrapper.unwrap(dataSource, PoolConfiguration.class,
 					DataSourceProxy.class);
 			if (dataSourceProxy != null) {
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourcePoolMetadataProvidersConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourcePoolMetadataProvidersConfiguration.java
index 7b18fcbca92..dfafe981f41 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourcePoolMetadataProvidersConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourcePoolMetadataProvidersConfiguration.java
@@ -23,6 +23,7 @@ import oracle.ucp.jdbc.PoolDataSource;
 import org.apache.commons.dbcp2.BasicDataSource;
 import org.apache.commons.dbcp2.BasicDataSourceMXBean;
 import org.apache.tomcat.jdbc.pool.jmx.ConnectionPoolMBean;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.aot.hint.RuntimeHints;
 import org.springframework.aot.hint.RuntimeHintsRegistrar;
@@ -123,7 +124,7 @@ public class DataSourcePoolMetadataProvidersConfiguration {
 	static class HikariDataSourcePoolMetadataRuntimeHints implements RuntimeHintsRegistrar {
 
 		@Override
-		public void registerHints(RuntimeHints hints, ClassLoader classLoader) {
+		public void registerHints(RuntimeHints hints, @Nullable ClassLoader classLoader) {
 			hints.reflection().registerType(HikariDataSource.class, (builder) -> builder.withField("pool"));
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceProperties.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceProperties.java
index be60068586a..ab4abc3e90f 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceProperties.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/DataSourceProperties.java
@@ -22,6 +22,8 @@ import java.util.UUID;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.BeanClassLoaderAware;
 import org.springframework.beans.factory.BeanCreationException;
 import org.springframework.beans.factory.InitializingBean;
@@ -47,6 +49,7 @@ import org.springframework.util.StringUtils;
 @ConfigurationProperties("spring.datasource")
 public class DataSourceProperties implements BeanClassLoaderAware, InitializingBean {
 
+	@SuppressWarnings("NullAway.Init")
 	private ClassLoader classLoader;
 
 	/**
@@ -58,49 +61,50 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * Datasource name to use if "generate-unique-name" is false. Defaults to "testdb"
 	 * when using an embedded database, otherwise null.
 	 */
-	private String name;
+	private @Nullable String name;
 
 	/**
 	 * Fully qualified name of the DataSource implementation to use. By default, a
 	 * connection pool implementation is auto-detected from the classpath.
 	 */
-	private Class<? extends DataSource> type;
+	private @Nullable Class<? extends DataSource> type;
 
 	/**
 	 * Fully qualified name of the JDBC driver. Auto-detected based on the URL by default.
 	 */
-	private String driverClassName;
+	private @Nullable String driverClassName;
 
 	/**
 	 * JDBC URL of the database.
 	 */
-	private String url;
+	private @Nullable String url;
 
 	/**
 	 * Login username of the database.
 	 */
-	private String username;
+	private @Nullable String username;
 
 	/**
 	 * Login password of the database.
 	 */
-	private String password;
+	private @Nullable String password;
 
 	/**
 	 * JNDI location of the datasource. Class, url, username and password are ignored when
 	 * set.
 	 */
-	private String jndiName;
+	private @Nullable String jndiName;
 
 	/**
 	 * Connection details for an embedded database. Defaults to the most suitable embedded
 	 * database that is available on the classpath.
 	 */
+	@SuppressWarnings("NullAway.Init")
 	private EmbeddedDatabaseConnection embeddedDatabaseConnection;
 
 	private Xa xa = new Xa();
 
-	private String uniqueName;
+	private @Nullable String uniqueName;
 
 	@Override
 	public void setBeanClassLoader(ClassLoader classLoader) {
@@ -136,19 +140,19 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 		this.generateUniqueName = generateUniqueName;
 	}
 
-	public String getName() {
+	public @Nullable String getName() {
 		return this.name;
 	}
 
-	public void setName(String name) {
+	public void setName(@Nullable String name) {
 		this.name = name;
 	}
 
-	public Class<? extends DataSource> getType() {
+	public @Nullable Class<? extends DataSource> getType() {
 		return this.type;
 	}
 
-	public void setType(Class<? extends DataSource> type) {
+	public void setType(@Nullable Class<? extends DataSource> type) {
 		this.type = type;
 	}
 
@@ -157,11 +161,11 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * @return the configured driver
 	 * @see #determineDriverClassName()
 	 */
-	public String getDriverClassName() {
+	public @Nullable String getDriverClassName() {
 		return this.driverClassName;
 	}
 
-	public void setDriverClassName(String driverClassName) {
+	public void setDriverClassName(@Nullable String driverClassName) {
 		this.driverClassName = driverClassName;
 	}
 
@@ -178,9 +182,10 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 		return driverClassName;
 	}
 
-	String findDriverClassName() {
+	@Nullable String findDriverClassName() {
 		if (StringUtils.hasText(this.driverClassName)) {
-			Assert.state(driverClassIsLoadable(), () -> "Cannot load driver class: " + this.driverClassName);
+			Assert.state(driverClassIsLoadable(this.driverClassName),
+					() -> "Cannot load driver class: " + this.driverClassName);
 			return this.driverClassName;
 		}
 		String driverClassName = null;
@@ -193,9 +198,9 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 		return driverClassName;
 	}
 
-	private boolean driverClassIsLoadable() {
+	private boolean driverClassIsLoadable(String driverClassName) {
 		try {
-			ClassUtils.forName(this.driverClassName, null);
+			ClassUtils.forName(driverClassName, null);
 			return true;
 		}
 		catch (UnsupportedClassVersionError ex) {
@@ -212,11 +217,11 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * @return the configured url
 	 * @see #determineUrl()
 	 */
-	public String getUrl() {
+	public @Nullable String getUrl() {
 		return this.url;
 	}
 
-	public void setUrl(String url) {
+	public void setUrl(@Nullable String url) {
 		this.url = url;
 	}
 
@@ -241,7 +246,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * Determine the name to used based on this configuration.
 	 * @return the database name to use or {@code null}
 	 */
-	public String determineDatabaseName() {
+	public @Nullable String determineDatabaseName() {
 		if (this.generateUniqueName) {
 			if (this.uniqueName == null) {
 				this.uniqueName = UUID.randomUUID().toString();
@@ -262,11 +267,11 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * @return the configured username
 	 * @see #determineUsername()
 	 */
-	public String getUsername() {
+	public @Nullable String getUsername() {
 		return this.username;
 	}
 
-	public void setUsername(String username) {
+	public void setUsername(@Nullable String username) {
 		this.username = username;
 	}
 
@@ -274,7 +279,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * Determine the username to use based on this configuration and the environment.
 	 * @return the username to use
 	 */
-	public String determineUsername() {
+	public @Nullable String determineUsername() {
 		if (StringUtils.hasText(this.username)) {
 			return this.username;
 		}
@@ -289,11 +294,11 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * @return the configured password
 	 * @see #determinePassword()
 	 */
-	public String getPassword() {
+	public @Nullable String getPassword() {
 		return this.password;
 	}
 
-	public void setPassword(String password) {
+	public void setPassword(@Nullable String password) {
 		this.password = password;
 	}
 
@@ -301,7 +306,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * Determine the password to use based on this configuration and the environment.
 	 * @return the password to use
 	 */
-	public String determinePassword() {
+	public @Nullable String determinePassword() {
 		if (StringUtils.hasText(this.password)) {
 			return this.password;
 		}
@@ -311,7 +316,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 		return null;
 	}
 
-	public String getJndiName() {
+	public @Nullable String getJndiName() {
 		return this.jndiName;
 	}
 
@@ -321,7 +326,7 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 	 * will be ignored when using JNDI lookups.
 	 * @param jndiName the JNDI name
 	 */
-	public void setJndiName(String jndiName) {
+	public void setJndiName(@Nullable String jndiName) {
 		this.jndiName = jndiName;
 	}
 
@@ -353,18 +358,18 @@ public class DataSourceProperties implements BeanClassLoaderAware, InitializingB
 		/**
 		 * XA datasource fully qualified name.
 		 */
-		private String dataSourceClassName;
+		private @Nullable String dataSourceClassName;
 
 		/**
 		 * Properties to pass to the XA data source.
 		 */
 		private Map<String, String> properties = new LinkedHashMap<>();
 
-		public String getDataSourceClassName() {
+		public @Nullable String getDataSourceClassName() {
 			return this.dataSourceClassName;
 		}
 
-		public void setDataSourceClassName(String dataSourceClassName) {
+		public void setDataSourceClassName(@Nullable String dataSourceClassName) {
 			this.dataSourceClassName = dataSourceClassName;
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/EmbeddedDataSourceConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/EmbeddedDataSourceConfiguration.java
index 312dda3abef..c9101059491 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/EmbeddedDataSourceConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/EmbeddedDataSourceConfiguration.java
@@ -23,6 +23,8 @@ import org.springframework.context.annotation.Bean;
 import org.springframework.context.annotation.Configuration;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabase;
 import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
+import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
+import org.springframework.util.Assert;
 
 /**
  * Configuration for embedded data sources.
@@ -36,6 +38,7 @@ import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseBuilder;
 @EnableConfigurationProperties(DataSourceProperties.class)
 public class EmbeddedDataSourceConfiguration implements BeanClassLoaderAware {
 
+	@SuppressWarnings("NullAway.Init")
 	private ClassLoader classLoader;
 
 	@Override
@@ -45,9 +48,11 @@ public class EmbeddedDataSourceConfiguration implements BeanClassLoaderAware {
 
 	@Bean(destroyMethod = "shutdown")
 	public EmbeddedDatabase dataSource(DataSourceProperties properties) {
-		return new EmbeddedDatabaseBuilder().setType(EmbeddedDatabaseConnection.get(this.classLoader).getType())
-			.setName(properties.determineDatabaseName())
-			.build();
+		EmbeddedDatabaseType type = EmbeddedDatabaseConnection.get(this.classLoader).getType();
+		String databaseName = properties.determineDatabaseName();
+		Assert.state(type != null, "'type' must not be null");
+		Assert.state(databaseName != null, "'databaseName' must not be null");
+		return new EmbeddedDatabaseBuilder().setType(type).setName(databaseName).build();
 	}
 
 }
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/HikariDriverConfigurationFailureAnalyzer.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/HikariDriverConfigurationFailureAnalyzer.java
index b8f888517ca..da8bd2e3ebc 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/HikariDriverConfigurationFailureAnalyzer.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/HikariDriverConfigurationFailureAnalyzer.java
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.jdbc.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.diagnostics.AbstractFailureAnalyzer;
 import org.springframework.boot.diagnostics.FailureAnalysis;
 import org.springframework.jdbc.CannotGetJdbcConnectionException;
@@ -31,7 +33,7 @@ class HikariDriverConfigurationFailureAnalyzer extends AbstractFailureAnalyzer<C
 	private static final String EXPECTED_MESSAGE = "cannot use driverClassName and dataSourceClassName together.";
 
 	@Override
-	protected FailureAnalysis analyze(Throwable rootFailure, CannotGetJdbcConnectionException cause) {
+	protected @Nullable FailureAnalysis analyze(Throwable rootFailure, CannotGetJdbcConnectionException cause) {
 		Throwable subCause = cause.getCause();
 		if (subCause == null || !EXPECTED_MESSAGE.equals(subCause.getMessage())) {
 			return null;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcConnectionDetails.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcConnectionDetails.java
index 7961d11a2ce..89010e3cc49 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcConnectionDetails.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcConnectionDetails.java
@@ -16,8 +16,11 @@
 
 package org.springframework.boot.jdbc.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.autoconfigure.service.connection.ConnectionDetails;
 import org.springframework.boot.jdbc.DatabaseDriver;
+import org.springframework.util.Assert;
 
 /**
  * Details required to establish a connection to an SQL service using JDBC.
@@ -33,13 +36,13 @@ public interface JdbcConnectionDetails extends ConnectionDetails {
 	 * Username for the database.
 	 * @return the username for the database
 	 */
-	String getUsername();
+	@Nullable String getUsername();
 
 	/**
 	 * Password for the database.
 	 * @return the password for the database
 	 */
-	String getPassword();
+	@Nullable String getPassword();
 
 	/**
 	 * JDBC url for the database.
@@ -56,7 +59,9 @@ public interface JdbcConnectionDetails extends ConnectionDetails {
 	 * @see DatabaseDriver#getDriverClassName()
 	 */
 	default String getDriverClassName() {
-		return DatabaseDriver.fromJdbcUrl(getJdbcUrl()).getDriverClassName();
+		String driverClassName = DatabaseDriver.fromJdbcUrl(getJdbcUrl()).getDriverClassName();
+		Assert.state(driverClassName != null, "'driverClassName' must not be null");
+		return driverClassName;
 	}
 
 	/**
@@ -67,7 +72,7 @@ public interface JdbcConnectionDetails extends ConnectionDetails {
 	 * @see DatabaseDriver#fromJdbcUrl(String)
 	 * @see DatabaseDriver#getXaDataSourceClassName()
 	 */
-	default String getXaDataSourceClassName() {
+	default @Nullable String getXaDataSourceClassName() {
 		return DatabaseDriver.fromJdbcUrl(getJdbcUrl()).getXaDataSourceClassName();
 	}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcProperties.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcProperties.java
index ff5c5fe6be7..d16e3643248 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcProperties.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JdbcProperties.java
@@ -19,6 +19,8 @@ package org.springframework.boot.jdbc.autoconfigure;
 import java.time.Duration;
 import java.time.temporal.ChronoUnit;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.context.properties.ConfigurationProperties;
 import org.springframework.boot.convert.DurationUnit;
 
@@ -65,7 +67,7 @@ public class JdbcProperties {
 		 * duration suffix is not specified, seconds will be used.
 		 */
 		@DurationUnit(ChronoUnit.SECONDS)
-		private Duration queryTimeout;
+		private @Nullable Duration queryTimeout;
 
 		/**
 		 * Whether results processing should be skipped. Can be used to optimize callable
@@ -108,11 +110,11 @@ public class JdbcProperties {
 			this.maxRows = maxRows;
 		}
 
-		public Duration getQueryTimeout() {
+		public @Nullable Duration getQueryTimeout() {
 			return this.queryTimeout;
 		}
 
-		public void setQueryTimeout(Duration queryTimeout) {
+		public void setQueryTimeout(@Nullable Duration queryTimeout) {
 			this.queryTimeout = queryTimeout;
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JndiDataSourceAutoConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JndiDataSourceAutoConfiguration.java
index 584865e3d52..b6f9e65c062 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JndiDataSourceAutoConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/JndiDataSourceAutoConfiguration.java
@@ -30,6 +30,7 @@ import org.springframework.jdbc.datasource.embedded.EmbeddedDatabaseType;
 import org.springframework.jdbc.datasource.lookup.JndiDataSourceLookup;
 import org.springframework.jmx.export.MBeanExporter;
 import org.springframework.jmx.support.JmxUtils;
+import org.springframework.util.Assert;
 
 /**
  * {@link EnableAutoConfiguration Auto-configuration} for a JNDI located
@@ -49,7 +50,9 @@ public final class JndiDataSourceAutoConfiguration {
 	@ConditionalOnMissingBean
 	DataSource dataSource(DataSourceProperties properties, ApplicationContext context) {
 		JndiDataSourceLookup dataSourceLookup = new JndiDataSourceLookup();
-		DataSource dataSource = dataSourceLookup.getDataSource(properties.getJndiName());
+		String jndiName = properties.getJndiName();
+		Assert.state(jndiName != null, "'jndiName' must not be null");
+		DataSource dataSource = dataSourceLookup.getDataSource(jndiName);
 		excludeMBeanIfNecessary(dataSource, "dataSource", context);
 		return dataSource;
 	}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/PropertiesJdbcConnectionDetails.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/PropertiesJdbcConnectionDetails.java
index 6558e5e3c87..ed822818a7e 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/PropertiesJdbcConnectionDetails.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/PropertiesJdbcConnectionDetails.java
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.jdbc.autoconfigure;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Adapts {@link DataSourceProperties} to {@link JdbcConnectionDetails}.
  *
@@ -30,12 +32,12 @@ final class PropertiesJdbcConnectionDetails implements JdbcConnectionDetails {
 	}
 
 	@Override
-	public String getUsername() {
+	public @Nullable String getUsername() {
 		return this.properties.determineUsername();
 	}
 
 	@Override
-	public String getPassword() {
+	public @Nullable String getPassword() {
 		return this.properties.determinePassword();
 	}
 
@@ -50,7 +52,7 @@ final class PropertiesJdbcConnectionDetails implements JdbcConnectionDetails {
 	}
 
 	@Override
-	public String getXaDataSourceClassName() {
+	public @Nullable String getXaDataSourceClassName() {
 		return (this.properties.getXa().getDataSourceClassName() != null)
 				? this.properties.getXa().getDataSourceClassName()
 				: JdbcConnectionDetails.super.getXaDataSourceClassName();
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/XADataSourceAutoConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/XADataSourceAutoConfiguration.java
index 7810474839b..f6cf726ef8d 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/XADataSourceAutoConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/XADataSourceAutoConfiguration.java
@@ -65,6 +65,7 @@ import org.springframework.util.StringUtils;
 @ConditionalOnMissingBean(DataSource.class)
 public final class XADataSourceAutoConfiguration implements BeanClassLoaderAware {
 
+	@SuppressWarnings("NullAway.Init")
 	private ClassLoader classLoader;
 
 	@Bean
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/DataSourceHealthContributorAutoConfiguration.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/DataSourceHealthContributorAutoConfiguration.java
index 08caedba101..9b0f74aef8b 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/DataSourceHealthContributorAutoConfiguration.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/DataSourceHealthContributorAutoConfiguration.java
@@ -26,6 +26,8 @@ import java.util.stream.Stream;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.beans.factory.ObjectProvider;
 import org.springframework.beans.factory.config.ConfigurableListableBeanFactory;
@@ -72,6 +74,7 @@ public final class DataSourceHealthContributorAutoConfiguration implements Initi
 
 	private final Collection<DataSourcePoolMetadataProvider> metadataProviders;
 
+	@SuppressWarnings("NullAway.Init")
 	private DataSourcePoolMetadataProvider poolMetadataProvider;
 
 	DataSourceHealthContributorAutoConfiguration(ObjectProvider<DataSourcePoolMetadataProvider> metadataProviders) {
@@ -114,7 +117,7 @@ public final class DataSourceHealthContributorAutoConfiguration implements Initi
 		return new DataSourceHealthIndicator(source, getValidationQuery(source));
 	}
 
-	private String getValidationQuery(DataSource source) {
+	private @Nullable String getValidationQuery(DataSource source) {
 		DataSourcePoolMetadata poolMetadata = this.poolMetadataProvider.getDataSourcePoolMetadata(source);
 		return (poolMetadata != null) ? poolMetadata.getValidationQuery() : null;
 	}
@@ -165,7 +168,7 @@ public final class DataSourceHealthContributorAutoConfiguration implements Initi
 		}
 
 		@Override
-		public HealthContributor getContributor(String name) {
+		public @Nullable HealthContributor getContributor(String name) {
 			return this.delegate.getContributor(name);
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/package-info.java
index 9f3415f3bfe..64cfd23343c 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/health/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for JDBC health.
  */
+@NullMarked
 package org.springframework.boot.jdbc.autoconfigure.health;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/metrics/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/metrics/package-info.java
index cba531b9eb0..47fb64edf57 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/metrics/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/metrics/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for JDBC metrics.
  */
+@NullMarked
 package org.springframework.boot.jdbc.autoconfigure.metrics;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/package-info.java
index 18748f5632b..624176d17f1 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/autoconfigure/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Auto-configuration for JDBC.
  */
+@NullMarked
 package org.springframework.boot.jdbc.autoconfigure;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/JdbcUrlBuilder.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/JdbcUrlBuilder.java
index b168cde2c79..bb935c7d8b4 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/JdbcUrlBuilder.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/JdbcUrlBuilder.java
@@ -16,6 +16,8 @@
 
 package org.springframework.boot.jdbc.docker.compose;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.docker.compose.core.RunningService;
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
@@ -61,11 +63,11 @@ class JdbcUrlBuilder {
 	 * @param database the database to connect to
 	 * @return a new JDBC URL
 	 */
-	String build(RunningService service, String database) {
+	String build(RunningService service, @Nullable String database) {
 		return urlFor(service, database);
 	}
 
-	private String urlFor(RunningService service, String database) {
+	private String urlFor(RunningService service, @Nullable String database) {
 		Assert.notNull(service, "'service' must not be null");
 		StringBuilder url = new StringBuilder("jdbc:%s://%s:%d".formatted(this.driverProtocol, service.host(),
 				service.ports().get(this.containerPort)));
@@ -91,7 +93,7 @@ class JdbcUrlBuilder {
 		url.append("?").append(parameters);
 	}
 
-	private String getParameters(RunningService service) {
+	private @Nullable String getParameters(RunningService service) {
 		return service.labels().get(PARAMETERS_LABEL);
 	}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresEnvironment.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresEnvironment.java
index d4cc1653a4e..1604b0e490d 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresEnvironment.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresEnvironment.java
@@ -18,6 +18,8 @@ package org.springframework.boot.jdbc.docker.compose;
 
 import java.util.Map;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.util.Assert;
 import org.springframework.util.StringUtils;
 
@@ -43,7 +45,7 @@ class PostgresEnvironment {
 
 	private final String username;
 
-	private final String password;
+	private final @Nullable String password;
 
 	private final String database;
 
@@ -62,7 +64,7 @@ class PostgresEnvironment {
 		return defaultValue;
 	}
 
-	private String extractPassword(Map<String, String> env) {
+	private @Nullable String extractPassword(Map<String, String> env) {
 		if (isUsingTrustHostAuthMethod(env)) {
 			return null;
 		}
@@ -81,7 +83,7 @@ class PostgresEnvironment {
 		return this.username;
 	}
 
-	String getPassword() {
+	@Nullable String getPassword() {
 		return this.password;
 	}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresJdbcDockerComposeConnectionDetailsFactory.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresJdbcDockerComposeConnectionDetailsFactory.java
index 58e25da83df..55723afca7c 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresJdbcDockerComposeConnectionDetailsFactory.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/PostgresJdbcDockerComposeConnectionDetailsFactory.java
@@ -19,6 +19,8 @@ package org.springframework.boot.jdbc.docker.compose;
 import java.net.URLEncoder;
 import java.nio.charset.StandardCharsets;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.boot.docker.compose.core.RunningService;
 import org.springframework.boot.docker.compose.service.connection.DockerComposeConnectionDetailsFactory;
 import org.springframework.boot.docker.compose.service.connection.DockerComposeConnectionSource;
@@ -74,7 +76,7 @@ class PostgresJdbcDockerComposeConnectionDetailsFactory
 		}
 
 		@Override
-		public String getPassword() {
+		public @Nullable String getPassword() {
 			return this.environment.getPassword();
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/package-info.java
index 1cb18cad141..0f46f69878a 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/docker/compose/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support for Docker Compose JDBC service connections.
  */
+@NullMarked
 package org.springframework.boot.jdbc.docker.compose;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/DataSourceHealthIndicator.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/DataSourceHealthIndicator.java
index 855f7a3d93c..2c9eb0c16aa 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/DataSourceHealthIndicator.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/DataSourceHealthIndicator.java
@@ -24,6 +24,8 @@ import java.util.List;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 import org.springframework.beans.factory.InitializingBean;
 import org.springframework.boot.health.contributor.AbstractHealthIndicator;
 import org.springframework.boot.health.contributor.Health;
@@ -51,11 +53,11 @@ import org.springframework.util.StringUtils;
  */
 public class DataSourceHealthIndicator extends AbstractHealthIndicator implements InitializingBean {
 
-	private DataSource dataSource;
+	private @Nullable DataSource dataSource;
 
-	private String query;
+	private @Nullable String query;
 
-	private JdbcTemplate jdbcTemplate;
+	private @Nullable JdbcTemplate jdbcTemplate;
 
 	/**
 	 * Create a new {@link DataSourceHealthIndicator} instance.
@@ -69,7 +71,7 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 	 * {@link DataSource}.
 	 * @param dataSource the data source
 	 */
-	public DataSourceHealthIndicator(DataSource dataSource) {
+	public DataSourceHealthIndicator(@Nullable DataSource dataSource) {
 		this(dataSource, null);
 	}
 
@@ -79,7 +81,7 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 	 * @param dataSource the data source
 	 * @param query the validation query to use (can be {@code null})
 	 */
-	public DataSourceHealthIndicator(DataSource dataSource, String query) {
+	public DataSourceHealthIndicator(@Nullable DataSource dataSource, @Nullable String query) {
 		super("DataSource health check failed");
 		this.dataSource = dataSource;
 		this.query = query;
@@ -102,7 +104,8 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 	}
 
 	private void doDataSourceHealthCheck(Health.Builder builder) {
-		builder.up().withDetail("database", getProduct());
+		Assert.state(this.jdbcTemplate != null, "'jdbcTemplate' must not be null");
+		builder.up().withDetail("database", getProduct(this.jdbcTemplate));
 		String validationQuery = this.query;
 		if (StringUtils.hasText(validationQuery)) {
 			builder.withDetail("validationQuery", validationQuery);
@@ -113,21 +116,21 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 		}
 		else {
 			builder.withDetail("validationQuery", "isValid()");
-			boolean valid = isConnectionValid();
+			boolean valid = isConnectionValid(this.jdbcTemplate);
 			builder.status((valid) ? Status.UP : Status.DOWN);
 		}
 	}
 
-	private String getProduct() {
-		return this.jdbcTemplate.execute((ConnectionCallback<String>) this::getProduct);
+	private String getProduct(JdbcTemplate jdbcTemplate) {
+		return jdbcTemplate.execute((ConnectionCallback<String>) this::getProduct);
 	}
 
 	private String getProduct(Connection connection) throws SQLException {
 		return connection.getMetaData().getDatabaseProductName();
 	}
 
-	private Boolean isConnectionValid() {
-		return this.jdbcTemplate.execute((ConnectionCallback<Boolean>) this::isConnectionValid);
+	private Boolean isConnectionValid(JdbcTemplate jdbcTemplate) {
+		return jdbcTemplate.execute((ConnectionCallback<Boolean>) this::isConnectionValid);
 	}
 
 	private Boolean isConnectionValid(Connection connection) throws SQLException {
@@ -156,7 +159,7 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 	 * Return the validation query or {@code null}.
 	 * @return the query
 	 */
-	public String getQuery() {
+	public @Nullable String getQuery() {
 		return this.query;
 	}
 
@@ -172,6 +175,12 @@ public class DataSourceHealthIndicator extends AbstractHealthIndicator implement
 			if (columns != 1) {
 				throw new IncorrectResultSetColumnCountException(1, columns);
 			}
+			return getResultSetValue(rs);
+		}
+
+		// RowMapper.mapRow isn't defined as @Nullable return type
+		@SuppressWarnings("NullAway")
+		private Object getResultSetValue(ResultSet rs) throws SQLException {
 			return JdbcUtils.getResultSetValue(rs, 1);
 		}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/package-info.java
index 8b08ab049fa..17a29b46ccc 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/health/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Health integration for JDBC.
  */
+@NullMarked
 package org.springframework.boot.jdbc.health;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/init/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/init/package-info.java
index bf8710e6a77..e643e1efdb1 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/init/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/init/package-info.java
@@ -18,4 +18,7 @@
  * Support for initialization of an SQL database using a JDBC {@link javax.sql.DataSource
  * DataSource}.
  */
+@NullMarked
 package org.springframework.boot.jdbc.init;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/AbstractDataSourcePoolMetadata.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/AbstractDataSourcePoolMetadata.java
index ef9b6169274..ee9c66c7476 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/AbstractDataSourcePoolMetadata.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/AbstractDataSourcePoolMetadata.java
@@ -18,6 +18,8 @@ package org.springframework.boot.jdbc.metadata;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * A base {@link DataSourcePoolMetadata} implementation.
  *
@@ -38,7 +40,7 @@ public abstract class AbstractDataSourcePoolMetadata<T extends DataSource> imple
 	}
 
 	@Override
-	public Float getUsage() {
+	public @Nullable Float getUsage() {
 		Integer maxSize = getMax();
 		Integer currentSize = getActive();
 		if (maxSize == null || currentSize == null) {
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/CompositeDataSourcePoolMetadataProvider.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/CompositeDataSourcePoolMetadataProvider.java
index 50fb9212c80..5b9a16a1b0e 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/CompositeDataSourcePoolMetadataProvider.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/CompositeDataSourcePoolMetadataProvider.java
@@ -22,6 +22,8 @@ import java.util.List;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * A {@link DataSourcePoolMetadataProvider} implementation that returns the first
  * {@link DataSourcePoolMetadata} that is found by one of its delegate.
@@ -38,12 +40,13 @@ public class CompositeDataSourcePoolMetadataProvider implements DataSourcePoolMe
 	 * collection of delegates to use.
 	 * @param providers the data source pool metadata providers
 	 */
-	public CompositeDataSourcePoolMetadataProvider(Collection<? extends DataSourcePoolMetadataProvider> providers) {
+	public CompositeDataSourcePoolMetadataProvider(
+			@Nullable Collection<? extends DataSourcePoolMetadataProvider> providers) {
 		this.providers = (providers != null) ? List.copyOf(providers) : Collections.emptyList();
 	}
 
 	@Override
-	public DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource) {
+	public @Nullable DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource) {
 		for (DataSourcePoolMetadataProvider provider : this.providers) {
 			DataSourcePoolMetadata metadata = provider.getDataSourcePoolMetadata(dataSource);
 			if (metadata != null) {
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadata.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadata.java
index 82e31e913f1..905f8e18a9b 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadata.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadata.java
@@ -18,6 +18,8 @@ package org.springframework.boot.jdbc.metadata;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provides access meta-data that is commonly available from most pooled
  * {@link DataSource} implementations.
@@ -41,14 +43,14 @@ public interface DataSourcePoolMetadata {
 	 * information to compute the poll usage.
 	 * @return the usage value or {@code null}
 	 */
-	Float getUsage();
+	@Nullable Float getUsage();
 
 	/**
 	 * Return the current number of active connections that have been allocated from the
 	 * data source or {@code null} if that information is not available.
 	 * @return the number of active connections or {@code null}
 	 */
-	Integer getActive();
+	@Nullable Integer getActive();
 
 	/**
 	 * Return the number of established but idle connections. Can also return {@code null}
@@ -57,7 +59,7 @@ public interface DataSourcePoolMetadata {
 	 * @since 2.2.0
 	 * @see #getActive()
 	 */
-	default Integer getIdle() {
+	default @Nullable Integer getIdle() {
 		return null;
 	}
 
@@ -67,21 +69,21 @@ public interface DataSourcePoolMetadata {
 	 * information is not available.
 	 * @return the maximum number of active connections or {@code null}
 	 */
-	Integer getMax();
+	@Nullable Integer getMax();
 
 	/**
 	 * Return the minimum number of idle connections in the pool or {@code null} if that
 	 * information is not available.
 	 * @return the minimum number of active connections or {@code null}
 	 */
-	Integer getMin();
+	@Nullable Integer getMin();
 
 	/**
 	 * Return the query to use to validate that a connection is valid or {@code null} if
 	 * that information is not available.
 	 * @return the validation query or {@code null}
 	 */
-	String getValidationQuery();
+	@Nullable String getValidationQuery();
 
 	/**
 	 * The default auto-commit state of connections created by this pool. If not set
@@ -89,6 +91,6 @@ public interface DataSourcePoolMetadata {
 	 * java.sql.Connection.setAutoCommit(boolean) method will not be called.)
 	 * @return the default auto-commit state or {@code null}
 	 */
-	Boolean getDefaultAutoCommit();
+	@Nullable Boolean getDefaultAutoCommit();
 
 }
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadataProvider.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadataProvider.java
index 890e4be7e63..970b17f2722 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadataProvider.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/DataSourcePoolMetadataProvider.java
@@ -18,6 +18,8 @@ package org.springframework.boot.jdbc.metadata;
 
 import javax.sql.DataSource;
 
+import org.jspecify.annotations.Nullable;
+
 /**
  * Provide a {@link DataSourcePoolMetadata} based on a {@link DataSource}.
  *
@@ -33,6 +35,6 @@ public interface DataSourcePoolMetadataProvider {
 	 * @param dataSource the data source
 	 * @return the data source pool metadata
 	 */
-	DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource);
+	@Nullable DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource);
 
 }
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/HikariDataSourcePoolMetadata.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/HikariDataSourcePoolMetadata.java
index e491d329b7d..95ee8c8db5c 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/HikariDataSourcePoolMetadata.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/HikariDataSourcePoolMetadata.java
@@ -20,6 +20,7 @@ import javax.sql.DataSource;
 
 import com.zaxxer.hikari.HikariDataSource;
 import com.zaxxer.hikari.pool.HikariPool;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.beans.DirectFieldAccessor;
 
@@ -36,9 +37,10 @@ public class HikariDataSourcePoolMetadata extends AbstractDataSourcePoolMetadata
 	}
 
 	@Override
-	public Integer getActive() {
+	public @Nullable Integer getActive() {
 		try {
-			return getHikariPool().getActiveConnections();
+			HikariPool hikariPool = getHikariPool();
+			return (hikariPool != null) ? hikariPool.getActiveConnections() : null;
 		}
 		catch (Exception ex) {
 			return null;
@@ -46,16 +48,17 @@ public class HikariDataSourcePoolMetadata extends AbstractDataSourcePoolMetadata
 	}
 
 	@Override
-	public Integer getIdle() {
+	public @Nullable Integer getIdle() {
 		try {
-			return getHikariPool().getIdleConnections();
+			HikariPool hikariPool = getHikariPool();
+			return (hikariPool != null) ? hikariPool.getIdleConnections() : null;
 		}
 		catch (Exception ex) {
 			return null;
 		}
 	}
 
-	private HikariPool getHikariPool() {
+	private @Nullable HikariPool getHikariPool() {
 		return (HikariPool) new DirectFieldAccessor(getDataSource()).getPropertyValue("pool");
 	}
 
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/OracleUcpDataSourcePoolMetadata.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/OracleUcpDataSourcePoolMetadata.java
index 578d33db257..fb077feebba 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/OracleUcpDataSourcePoolMetadata.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/OracleUcpDataSourcePoolMetadata.java
@@ -21,6 +21,7 @@ import java.sql.SQLException;
 import javax.sql.DataSource;
 
 import oracle.ucp.jdbc.PoolDataSource;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.util.StringUtils;
 
@@ -37,7 +38,7 @@ public class OracleUcpDataSourcePoolMetadata extends AbstractDataSourcePoolMetad
 	}
 
 	@Override
-	public Integer getActive() {
+	public @Nullable Integer getActive() {
 		try {
 			return getDataSource().getBorrowedConnectionsCount();
 		}
@@ -47,7 +48,7 @@ public class OracleUcpDataSourcePoolMetadata extends AbstractDataSourcePoolMetad
 	}
 
 	@Override
-	public Integer getIdle() {
+	public @Nullable Integer getIdle() {
 		try {
 			return getDataSource().getAvailableConnectionsCount();
 		}
@@ -72,7 +73,7 @@ public class OracleUcpDataSourcePoolMetadata extends AbstractDataSourcePoolMetad
 	}
 
 	@Override
-	public Boolean getDefaultAutoCommit() {
+	public @Nullable Boolean getDefaultAutoCommit() {
 		String autoCommit = getDataSource().getConnectionProperty("autoCommit");
 		return StringUtils.hasText(autoCommit) ? Boolean.valueOf(autoCommit) : null;
 	}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/package-info.java
index 3c82c100502..0865a42e778 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metadata/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support for accessing JDBC {@link javax.sql.DataSource} metadata.
  */
+@NullMarked
 package org.springframework.boot.jdbc.metadata;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/DataSourcePoolMetrics.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/DataSourcePoolMetrics.java
index a496a8699dc..18d5267e066 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/DataSourcePoolMetrics.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/DataSourcePoolMetrics.java
@@ -27,6 +27,7 @@ import io.micrometer.core.instrument.MeterRegistry;
 import io.micrometer.core.instrument.Tag;
 import io.micrometer.core.instrument.Tags;
 import io.micrometer.core.instrument.binder.MeterBinder;
+import org.jspecify.annotations.Nullable;
 
 import org.springframework.boot.jdbc.metadata.CompositeDataSourcePoolMetadataProvider;
 import org.springframework.boot.jdbc.metadata.DataSourcePoolMetadata;
@@ -64,6 +65,7 @@ public class DataSourcePoolMetrics implements MeterBinder {
 	}
 
 	@Override
+	@SuppressWarnings("NullAway") // Lambda isn't detected with the correct nullability
 	public void bindTo(MeterRegistry registry) {
 		if (this.metadataProvider.getDataSourcePoolMetadata(this.dataSource) != null) {
 			bindPoolMetadata(registry, "active",
@@ -79,18 +81,20 @@ public class DataSourcePoolMetrics implements MeterBinder {
 		}
 	}
 
+	@SuppressWarnings("NullAway") // Lambda isn't detected with the correct nullability
 	private <N extends Number> void bindPoolMetadata(MeterRegistry registry, String metricName, String description,
-			Function<DataSourcePoolMetadata, N> function) {
+			Function<DataSourcePoolMetadata, @Nullable N> function) {
 		bindDataSource(registry, metricName, description, this.metadataProvider.getValueFunction(function));
 	}
 
 	private <N extends Number> void bindDataSource(MeterRegistry registry, String metricName, String description,
-			Function<DataSource, N> function) {
+			Function<DataSource, @Nullable N> function) {
 		if (function.apply(this.dataSource) != null) {
-			Gauge.builder("jdbc.connections." + metricName, this.dataSource, (m) -> function.apply(m).doubleValue())
-				.tags(this.tags)
-				.description(description)
-				.register(registry);
+			Gauge.builder("jdbc.connections." + metricName, this.dataSource, (m) -> {
+				Number value = function.apply(m);
+				Assert.state(value != null, "'value' must not be null");
+				return value.doubleValue();
+			}).tags(this.tags).description(description).register(registry);
 		}
 	}
 
@@ -104,12 +108,17 @@ public class DataSourcePoolMetrics implements MeterBinder {
 			this.metadataProvider = metadataProvider;
 		}
 
-		<N extends Number> Function<DataSource, N> getValueFunction(Function<DataSourcePoolMetadata, N> function) {
-			return (dataSource) -> function.apply(getDataSourcePoolMetadata(dataSource));
+		<N extends Number> Function<DataSource, @Nullable N> getValueFunction(
+				Function<DataSourcePoolMetadata, @Nullable N> function) {
+			return (dataSource) -> {
+				DataSourcePoolMetadata dataSourcePoolMetadata = getDataSourcePoolMetadata(dataSource);
+				Assert.state(dataSourcePoolMetadata != null, "'dataSourcePoolMetadata' must not be null");
+				return function.apply(dataSourcePoolMetadata);
+			};
 		}
 
 		@Override
-		public DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource) {
+		public @Nullable DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource) {
 			return cache.computeIfAbsent(dataSource,
 					(key) -> this.metadataProvider.getDataSourcePoolMetadata(dataSource));
 		}
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/package-info.java
index 6f9f61e739e..b0901680d2f 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/metrics/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Metrics for JDBC.
  */
+@NullMarked
 package org.springframework.boot.jdbc.metrics;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/package-info.java
index 9edb08fedc5..d5b12b9bf35 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support for Java Database Connectivity (JDBC).
  */
+@NullMarked
 package org.springframework.boot.jdbc;
+
+import org.jspecify.annotations.NullMarked;
diff --git a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/testcontainers/package-info.java b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/testcontainers/package-info.java
index 03956e55e9f..0260522a250 100644
--- a/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/testcontainers/package-info.java
+++ b/module/spring-boot-jdbc/src/main/java/org/springframework/boot/jdbc/testcontainers/package-info.java
@@ -17,4 +17,7 @@
 /**
  * Support for testcontainers JDBC service connections.
  */
+@NullMarked
 package org.springframework.boot.jdbc.testcontainers;
+
+import org.jspecify.annotations.NullMarked;