Bug 135778 There is an error when the data item has no binding data set
Data item can have no binding data set, if it happens, it indicates it only use the basic Java Script function such as new Date(). At this moment, the data of data item is not stored in report document by DtE, which only supports these data items which has binding data set.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/executor/transform/group/GroupCalculationUtil.java
{
	private BaseQuery query;
	private IResultClass rsMeta;
	/**
	 * Group definitions. Each entry has name of key column plus interval
	 * information. groupKeys[0] is the highest group level
	 */
	private GroupBy[] groupDefs;
	
	private ResultSetCache smartCache;
	private GroupInformationUtil groupInformationUtil;
	/*
	 * groups[level] is an ArrayList of GroupInfo objects at the specified
	 * level. Level is a 0-based group index, with 0 denoting the outermost
	 * group, etc. Example: Row GroupKey1 GroupKey2 GroupKey3 Column4 Column5 0:
	 * CHINA BEIJING 2003 Cola $100 1: CHINA BEIJING 2003 Pizza $320 2: CHINA
	 * BEIJING 2004 Cola $402 3: CHINA SHANGHAI 2003 Cola $553 4: CHINA SHANGHAI
	 * 2003 Pizza $223 5: CHINA SHANGHAI 2004 Cola $226 6: USA CHICAGO 2004
	 * Pizza $133 7: USA NEW YORK 2004 Cola $339 8: USA NEW YORK 2004 Cola $297
	 * 
	 * groups: (parent, child) LEVEL 0 LEVEL 1 LEVEL 2
	 * ============================================ 0: -,0 0,0 0,0 1: -,2 0,2
	 * 0,2 2: 1,4 1,3 3: 1,5 1,5 4: 2,6 5: 3,7
	 */
	private ResultSetPopulator resultPopoulator;
	
	/**
	 *