Bug 208419 NullPointerException at CubeResultSet close
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/DataPresentationEngine.java
{
		keyBuffer.setLength( 0 );
		keyBuffer.append( pRsetId );
		keyBuffer.append( "." );
		keyBuffer.append( rawId );
		keyBuffer.append( "." );
		keyBuffer.append( queryId );
		
		String rsetId = (String) rsetRelations.get( keyBuffer.toString( ) );		
		return rsetId;
	}
	protected IBaseResultSet doExecuteQuery( IBaseResultSet parentResult,
			IQueryDefinition query, boolean useCache )
	{
		String queryID = (String) queryIDMap.get( query );
		try
		{
			String resultSetID = loadResultSetID( parentResult, queryID );
			if ( resultSetID == null )
			{
				logger.log( Level.SEVERE, "Can't load the report query" );
				return null;
			}
			IBaseQueryResults queryResults = dteSession.getQueryResults( resultSetID );
			QueryResultSet resultSet = null;
			if ( parentResult == null )
			{
				
				resultSet = new QueryResultSet( this, context,
							query,