Updating to work with java 1.6

Author: sk02241994

src/main/java/org/json/JSONObject.java

@@ -3529,8 +3529,8 @@ public Map create() {
     private <E extends Enum<E>> E stringToEnum(Class<?> enumClass, String value) throws JSONException {
         try {
             @SuppressWarnings("unchecked")
-            Method valueOfMethod = enumClass.getMethod("valueOf", String.class);
-            return (E) valueOfMethod.invoke(null, value);
+            Class<E> enumType = (Class<E>) enumClass;
+            return Enum.valueOf(enumType, value);
         } catch (Exception e) {
             throw new JSONException("Failed to convert string to enum: " + value + " for " + enumClass.getName(), e);
         }