Make TypeSafeEnum immutable

Signed-off-by: Alexander Kriegisch <Alexander@Kriegisch.name>

util/src/main/java/org/aspectj/util/TypeSafeEnum.java

 import java.io.IOException;
 
 public class TypeSafeEnum {
-	private byte key;
-	private String name;
+	private final byte key;
+	private final String name;
 
 	public TypeSafeEnum(String name, int key) {
 		this.name = name;
 	@Override
 	public boolean equals(Object o) {
 		return (o instanceof TypeSafeEnum) &&
-			   ((TypeSafeEnum)o).key == key &&
-			   ((TypeSafeEnum)o).name.equals(name);
+			((TypeSafeEnum)o).key == key &&
+			((TypeSafeEnum)o).name.equals(name);
 	}
 }