code: private void updateRelatedObjectSet(APIPatch.Operation operation,
              RelatedObjectSetPatch relatedObjectSetPatch, String identifier)
              throws GuacamoleException {
  
          // Add or remove object based on operation
          switch (operation) {
  
              // Add object
              case add:
                  relatedObjectSetPatch.addObject(identifier);
                  break;
  
              // Remove object
              case remove:
                  relatedObjectSetPatch.removeObject(identifier);
                  break;
  
              // Unsupported patch operation
              default:
                  throw new GuacamoleClientException("Unsupported patch operation: \"" + operation + "\"");
  
          }
  
      }
docs: Updates the given RelatedObjectSetPatch by queuing an add or remove
  operation for the object having the given identifier based on the given
  patch operation.
  
  @param operation
  The patch operation to perform.
  
  @param relatedObjectSetPatch
  The RelatedObjectSetPatch being modified.
  
  @param identifier
  The identifier of the object being added or removed from the set.
  
  @throws GuacamoleException
  If the requested patch operation is not supported.