Update to NullAway 0.14.0 and fix new warnings

See gh-37188

Signed-off-by: Manu Sridharan <msridhar@gmail.com>

spring-core/src/main/java/org/springframework/core/convert/converter/ConvertingComparator.java

@@ -69,6 +69,7 @@ public class ConvertingComparator<S, T extends @Nullable Object> implements Comp
 	 * @param conversionService the conversion service
 	 * @param targetType the target type
 	 */
+	@SuppressWarnings("NullAway") // Retain support for comparators that handle a null conversion result
 	public ConvertingComparator(
 			Comparator<T> comparator, ConversionService conversionService, Class<? extends T> targetType) {
 

spring-core/src/main/java/org/springframework/core/convert/support/CharacterToNumberFactory.java

@@ -43,7 +43,7 @@ import org.springframework.util.NumberUtils;
 final class CharacterToNumberFactory implements ConverterFactory<Character, Number> {
 
 	@Override
-	public <T extends Number> Converter<Character, @Nullable T> getConverter(Class<T> targetType) {
+	public <T extends Number> Converter<Character, ? extends @Nullable T> getConverter(Class<T> targetType) {
 		return new CharacterToNumber<>(targetType);
 	}
 

spring-core/src/main/java/org/springframework/core/convert/support/NumberToNumberConverterFactory.java

@@ -45,7 +45,7 @@ import org.springframework.util.NumberUtils;
 final class NumberToNumberConverterFactory implements ConverterFactory<Number, Number>, ConditionalConverter {
 
 	@Override
-	public <T extends Number> Converter<Number, @Nullable T> getConverter(Class<T> targetType) {
+	public <T extends Number> Converter<Number, ? extends @Nullable T> getConverter(Class<T> targetType) {
 		return new NumberToNumber<>(targetType);
 	}
 

spring-core/src/main/java/org/springframework/core/task/SimpleAsyncTaskExecutor.java

@@ -345,7 +345,7 @@ public class SimpleAsyncTaskExecutor extends CustomizableThreadCreator
 
 	@SuppressWarnings("deprecation")
 	@Override
-	public <T> Future<T> submit(Callable<T> task) {
+	public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
 		FutureTask<T> future = new FutureTask<>(task);
 		execute(future, TIMEOUT_INDEFINITE);
 		return future;

spring-core/src/main/java/org/springframework/core/task/support/TaskExecutorAdapter.java

@@ -113,7 +113,7 @@ public class TaskExecutorAdapter implements AsyncTaskExecutor {
 	}
 
 	@Override
-	public <T> Future<T> submit(Callable<T> task) {
+	public <T extends @Nullable Object> Future<T> submit(Callable<T> task) {
 		try {
 			if (this.taskDecorator == null &&
 					this.concurrentExecutor instanceof ExecutorService executorService) {

spring-core/src/main/java/org/springframework/util/LinkedCaseInsensitiveMap.java

@@ -48,7 +48,7 @@ import org.jspecify.annotations.Nullable;
  * @since 3.0
  * @param <V> the value type
  */
-public class LinkedCaseInsensitiveMap<V> implements Map<String, V>, Serializable, Cloneable {
+public class LinkedCaseInsensitiveMap<V extends @Nullable Object> implements Map<String, V>, Serializable, Cloneable {
 
 	@Serial
 	private static final long serialVersionUID = -1797561627545787622L;

spring-core/src/main/java/org/springframework/util/comparator/InstanceComparator.java

@@ -37,7 +37,7 @@ import org.springframework.util.Assert;
  * @param <T> the type of objects that may be compared by this comparator
  * @see Comparator#thenComparing(Comparator)
  */
-public class InstanceComparator<T> implements Comparator<T> {
+public class InstanceComparator<T extends @Nullable Object> implements Comparator<T> {
 
 	private final Class<?>[] instanceOrder;