Bug 182680 Use feature of new Aggregation framework of Data Engine.
DataEngine will implement new aggregation framework in 2.2.0RC0. After the implementation is finished Engine should go ahead to use new column bindings in definition of map/highlight.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/api/impl/DataExtractionTask.java
protected Report report;
	/**
	 * selected instance id
	 */
	protected InstanceID instanceId;
	/**
	 * selected rest set
	 */
	protected String resultSetName;
	/**
	 * selected columns
	 */
	protected String[] selectedColumns;
	/**
	 * current extaction results
	 */
	protected IExtractionResults currentResult = null;
	
	/**
	 * simple filter expression
	 */
	protected IFilterDefinition[] filterExpressions = null;
	/**
	 * have the metadata be prepared. meta data means rsetName2IdMapping and
	 * queryId2NameMapping
	 */
	protected boolean isMetaDataPrepared = false;
	/**
	 * mapping, map the rest name to rset id.
	 */