SPR-8718 Prevent Converter<?,?> from converting target sub-type.

org.springframework.core/src/main/java/org/springframework/core/convert/support/GenericConversionService.java

@@ -500,6 +500,10 @@ public class GenericConversionService implements ConfigurableConversionService {
 			return Collections.singleton(this.typeInfo);
 		}
 
+		public boolean matchesTargetType(TypeDescriptor targetType) {
+			return this.typeInfo.getTargetType().equals(targetType.getObjectType());
+		}
+
 		public Object convert(Object source, TypeDescriptor sourceType, TypeDescriptor targetType) {
 			if (source == null) {
 				return convertNullSource(sourceType, targetType);
@@ -571,6 +575,12 @@ public class GenericConversionService implements ConfigurableConversionService {
 					}
 				}
 			}
+			if (this.defaultConverter instanceof ConverterAdapter) {
+				ConverterAdapter adapter = (ConverterAdapter) this.defaultConverter;
+				if (!adapter.matchesTargetType(targetType)) {
+					return null;
+				}
+			}
 			return this.defaultConverter;
 		}
 

org.springframework.core/src/test/java/org/springframework/core/convert/support/GenericConversionServiceTests.java

@@ -210,7 +210,6 @@ public class GenericConversionServiceTests {
 	// SPR-8718
 	
 	@Test(expected=ConverterNotFoundException.class)
-	@Ignore("TODO")
 	public void convertSuperTarget() {
 		conversionService.addConverter(new ColorConverter());
 		conversionService.convert("#000000", SystemColor.class);