ConversionService prevents Converter from trying to convert to a subtype of its actual target type (SPR-8718)

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

@@ -428,6 +428,10 @@ public class GenericConversionService implements ConversionService, ConverterReg
 			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);
@@ -498,6 +502,12 @@ public class GenericConversionService implements ConversionService, ConverterReg
 					}
 				}
 			}
+			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

@@ -16,6 +16,8 @@
 
 package org.springframework.core.convert.support;
 
+import java.awt.Color;
+import java.awt.SystemColor;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.HashMap;
@@ -138,6 +140,18 @@ public class GenericConversionServiceTests {
 		assertEquals(new Integer(3), result);
 	}
 
+	// SPR-8718
+
+	@Test(expected=ConverterNotFoundException.class)
+	public void convertSuperTarget() {
+		conversionService.addConverter(new ColorConverter());
+		conversionService.convert("#000000", SystemColor.class).getClass();
+	}
+
+	public class ColorConverter implements Converter<String, Color> {
+		public Color convert(String source) { if (!source.startsWith("#")) source = "#" + source; return Color.decode(source); }
+	}
+
 	@Test
 	public void convertObjectToPrimitive() {
 		assertFalse(conversionService.canConvert(String.class, boolean.class));