@Override
  public void onAddNotNullConstraint(AddNotNullConstraintEvent addNotNullConstraintEvent) throws MetaException {
    List<SQLNotNullConstraint> cols = addNotNullConstraintEvent.getNotNullConstraintCols();
    if (cols.size() > 0) {
      AddNotNullConstraintMessage msg = MessageBuilder.getInstance()
          .buildAddNotNullConstraintMessage(addNotNullConstraintEvent.getNotNullConstraintCols());
      NotificationEvent event =
          new NotificationEvent(0, now(), EventType.ADD_NOTNULLCONSTRAINT.toString(),
              msgEncoder.getSerializer().serialize(msg)
          );
      event.setCatName(cols.get(0).isSetCatName() ? cols.get(0).getCatName() : getDefaultCatalog(conf));
      event.setDbName(cols.get(0).getTable_db());
      event.setTableName(cols.get(0).getTable_name());
      process(event, addNotNullConstraintEvent);
    }
  }
@param addNotNullConstraintEvent add not null constraint event
@throws MetaException
hcatalog/server-extensions/src/main/java/org/apache/hive/hcatalog/listener/DbNotificationListener.java