Bug 208419 NullPointerException at CubeResultSet close
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/data/dte/DataInteractiveEngine.java
buffer.append( pRsetId );
				buffer.append( "." );
				buffer.append( rowId );
				buffer.append( "." );
				buffer.append( queryId );
				rsetRelations.put( buffer.toString( ), rsetId );
			}
		}
	}
	private StringBuffer keyBuffer = new StringBuffer( );
	protected String getResultID( String pRsetId, String rowId, String queryId )
	{
		keyBuffer.setLength( 0 );
		keyBuffer.append( pRsetId );
		keyBuffer.append( "." );
		keyBuffer.append( rowId );
		keyBuffer.append( "." );
		keyBuffer.append( queryId );
		
		String rsetId = (String) rsetRelations.get( keyBuffer.toString( ) );
		if ( rsetId == null )
		{
			if ( pRsetId != null )
			{
				int charAt = pRsetId.indexOf( "_" );
				if ( charAt != -1 )
				{
					String rootId = pRsetId.substring( 0, charAt );
					keyBuffer.setLength( 0 );
					keyBuffer.append( rootId );