/**
  * Computes the hashcode for this object.
  *
  * @return Hashcode for this object.
  */
 @Override
 public int hashCode() {
   final int prime = 31;
   int result = super.hashCode();
   result = prime * result + ((operation == null) ? 0 : operation.hashCode());
   return result;
 }
 /** @see rexos.HAL.libraries.blackboard_client.BlackboardSubscription#getQuery() */
 @Override
 public DBObject getQuery() {
   return QueryBuilder.start(OplogEntry.OPERATION_FIELD).is(operation.getOpCode()).get();
 }