@SuppressWarnings("unchecked")
  private <A extends ClusterManagementOperation<V>, V extends OperationResult> OperationPerformer<A, V> getPerformer(
      A op) {
    return performers.get(op.getClass());
  }
for use by modules/extensions to install custom cluster management operations
geode-core/src/main/java/org/apache/geode/management/internal/operation/OperationManager.java