code: public static ModelNode getFailureDescription(final ModelNode result) {
          if (isSuccessfulOutcome(result)) {
              throw ControllerClientLogger.ROOT_LOGGER.noFailureDescription();
          }
          if (result.hasDefined(FAILURE_DESCRIPTION)) {
              return result.get(FAILURE_DESCRIPTION);
          }
          return new ModelNode();
      }
docs: Parses the result and returns the failure description.
  
  @param result the result of executing an operation
  
  @return the failure description if defined, otherwise a new undefined model node
  
  @throws IllegalArgumentException if the outcome of the operation was successful