Merge pull request #50773 from xfocus3

Closes gh-50773

* pr/50773:
  Polish 'Bind empty strings to empty maps'
  Bind empty strings to empty maps

core/spring-boot/src/main/java/org/springframework/boot/context/properties/bind/MapBinder.java

@@ -39,6 +39,7 @@ import org.springframework.core.ResolvableType;
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Ahmed El Amraouiyine
  */
 class MapBinder extends AggregateBinder<Map<Object, Object>> {
 
@@ -64,6 +65,9 @@ class MapBinder extends AggregateBinder<Map<Object, Object>> {
 				if (property != null) {
 					getContext().setConfigurationProperty(property);
 					Object result = getContext().getPlaceholdersResolver().resolvePlaceholders(property.getValue());
+					if (result instanceof CharSequence charSequence && charSequence.isEmpty()) {
+						return createMap(target);
+					}
 					return getContext().getConverter().convert(result, target);
 				}
 			}

core/spring-boot/src/test/java/org/springframework/boot/context/properties/bind/MapBinderTests.java

@@ -65,6 +65,7 @@ import static org.mockito.Mockito.mock;
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Ahmed El Amraouiyine
  */
 class MapBinderTests {
 
@@ -274,6 +275,15 @@ class MapBinderTests {
 		assertThat(result.isBound()).isFalse();
 	}
 
+	@Test
+	void bindToMapWhenEmptyStringShouldReturnEmptyMap() {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("foo", "");
+		this.sources.add(source);
+		Map<String, String> result = this.binder.bind("foo", STRING_STRING_MAP).get();
+		assertThat(result).isEmpty();
+	}
+
 	@Test
 	void bindToMapShouldConvertKey() {
 		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
@@ -510,6 +520,17 @@ class MapBinderTests {
 		assertThat(foo2.getValue()).isEqualTo("three");
 	}
 
+	@Test
+	void nestedMapsWhenEmptyStringShouldReturnEmptyMap() {
+		MockConfigurationPropertySource source = new MockConfigurationPropertySource();
+		source.put("foo.value", "one");
+		source.put("foo.foos", "");
+		this.sources.add(source);
+		BindResult<NestableFoo> foo = this.binder.bind("foo", NestableFoo.class);
+		assertThat(foo.get().getValue()).isEqualTo("one");
+		assertThat(foo.get().getFoos()).isEmpty();
+	}
+
 	@Test
 	void bindToMapWithCustomConverter() {
 		DefaultConversionService conversionService = new DefaultConversionService();