code: @Override
      public DBInstance promoteReadReplica(PromoteReadReplicaRequest request) {
          request = beforeClientExecution(request);
          return executePromoteReadReplica(request);
      }
docs: <p>
  Promotes a Read Replica DB instance to a standalone DB instance.
  </p>
  <note>
  <ul>
  <li>
  <p>
  Backup duration is a function of the amount of changes to the database since the previous backup. If you plan to
  promote a Read Replica to a standalone instance, we recommend that you enable backups and complete at least one
  backup prior to promotion. In addition, a Read Replica cannot be promoted to a standalone instance when it is in
  the <code>backing-up</code> status. If you have enabled backups on your Read Replica, configure the automated
  backup window so that daily backups do not interfere with Read Replica promotion.
  </p>
  </li>
  <li>
  <p>
  This command doesn't apply to Aurora MySQL and Aurora PostgreSQL.
  </p>
  </li>
  </ul>
  </note>
  
  @param promoteReadReplicaRequest
  @return Result of the PromoteReadReplica operation returned by the service.
  @throws InvalidDBInstanceStateException
  The DB instance isn't in a valid state.
  @throws DBInstanceNotFoundException
  <i>DBInstanceIdentifier</i> doesn't refer to an existing DB instance.
  @sample AmazonRDS.PromoteReadReplica
  @see <a href="http://docs.aws.amazon.com/goto/WebAPI/rds-2014-10-31/PromoteReadReplica" target="_top">AWS API
  Documentation</a>