Bug 182061 Data engine changes to support result set sharing
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/api/IBaseQueryDefinition.java
{
	/**
	 * Returns the group definitions as an ordered collection of 
	 * {@link org.eclipse.birt.data.engine.api.IGroupDefinition}
	 * objects. Groups are organizations within the data that support
	 * aggregation, filtering and sorting. Reports use groups to trigger
	 * level breaks.
	 * 
	 * @return the list of groups. If no group is defined, null is returned.
	 */
	
	public List getGroups( );