Polish 'Bind empty strings to empty maps'

See gh-50773

Author: philwebb

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

@@ -33,13 +33,13 @@
 import org.springframework.boot.context.properties.source.IterableConfigurationPropertySource;
 import org.springframework.core.CollectionFactory;
 import org.springframework.core.ResolvableType;
-import org.springframework.util.ObjectUtils;
 
 /**
  * {@link AggregateBinder} for Maps.
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Ahmed El Amraouiyine
  */
 class MapBinder extends AggregateBinder<Map<Object, Object>> {
 
@@ -65,7 +65,7 @@ protected boolean isAllowRecursiveBinding(@Nullable ConfigurationPropertySource
 				if (property != null) {
 					getContext().setConfigurationProperty(property);
 					Object result = getContext().getPlaceholdersResolver().resolvePlaceholders(property.getValue());
-					if (ObjectUtils.isEmpty(result)) {
+					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 @@
  *
  * @author Phillip Webb
  * @author Madhura Bhave
+ * @author Ahmed El Amraouiyine
  */
 class MapBinderTests {