turned TypeDescriptor.UNKNOWN into an internal detail (SPR-7349)

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@3507 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.core/src/main/java/org/springframework/core/convert/TypeDescriptor.java

@@ -43,7 +43,7 @@ public class TypeDescriptor {
 	public static final TypeDescriptor NULL = new TypeDescriptor();
 
 	/** Constant defining a TypeDescriptor for 'unknown type' */
-	public static final TypeDescriptor UNKNOWN = new TypeDescriptor(Object.class);
+	private static final TypeDescriptor UNKNOWN = new TypeDescriptor(Object.class);
 
 	private static final Map<Class<?>, TypeDescriptor> typeDescriptorCache = new HashMap<Class<?>, TypeDescriptor>();
 

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

@@ -118,11 +118,11 @@ public class PropertyTypeDescriptor extends TypeDescriptor {
 	}
 
 	public TypeDescriptor forElementType(Class<?> elementType) {
-		if (elementType == null) {
-			return TypeDescriptor.UNKNOWN;
+		if (elementType != null) {
+			return new PropertyTypeDescriptor(this.propertyDescriptor, getMethodParameter(), elementType);
 		}
 		else {
-			return new PropertyTypeDescriptor(this.propertyDescriptor, getMethodParameter(), elementType);
+			return super.forElementType(null);
 		}
 	}