private static void validate(AttributeDefinition ad, ModelNode operation, boolean expectFail) {
   try {
     ad.validateOperation(operation);
     if (expectFail) {
       fail("Didn't fail validation");
     }
   } catch (OperationFailedException ofe) {
     if (!expectFail) {
       fail("Failed validation " + ofe.toString());
     }
   }
 }