added superfluous cast as a workaround for the Sun Javac compiler

git-svn-id: https://src.springframework.org/svn/spring-framework/trunk@796 50f2f4bb-b051-0410-bef5-90022cba6387

org.springframework.core/src/main/java/org/springframework/core/convert/converter/StringToEnum.java

@@ -17,18 +17,19 @@ package org.springframework.core.convert.converter;
 
 /**
  * Converts a String to a Enum using {@link Enum#valueOf(Class, String)}.
- * 
+ *
  * @author Keith Donald
+ * @since 3.0
  */
 @SuppressWarnings("unchecked")
 public class StringToEnum implements SuperTwoWayConverter<String, Enum> {
 
 	public <RT extends Enum> RT convert(String source, Class<RT> targetClass) throws Exception {
-		return Enum.valueOf(targetClass, source);
+		return (RT) Enum.valueOf(targetClass, source);
 	}
 
 	public <RS extends String> RS convertBack(Enum target, Class<RS> sourceClass) throws Exception {
 		return (RS) target.name();
 	}
 
-}
+}