Bug 153506 Strange error message when group key refers to bad binding column name
Run attached report design. The following error is shown: Group key "groupkey" in group 1 cannot depend on column bindings defined in the group lower than itself. This is a strange error. Since the actual problem is that the table's binding column "groupkey" is defined to refer to another existing binding: row["bad"]. EXPECTED BEHAVIOR: The error message should clearly indicate that a non-existing binding is the cause of the failure.
data/org.eclipse.birt.data/src/org/eclipse/birt/data/engine/impl/ExprManagerUtil.java
*/
	private Node[] populateNodeList( Node[] source )
	{
		Node[] result = new Node[source.length];
		for ( int i = 0; i < result.length; i++ )
		{
			result[i] = new Node( source[i].getValue( ) );
		}
		for ( int i = 0; i < result.length; i++ )
		{
			List l = source[i].getChildren( );
			for ( int j = 0; j < l.size( ); j++ )
			{
				Node n = getMatchedNode( (Node) l.get( j ), result );
				
				if( n!= null )
					result[i].addChild( n );
			}
		}
		return result;
	}
	/**
	 * 
	 * @param node
	 * @param nodes
	 * @return
	 */
	private Node getMatchedNode( Node node, Node[] nodes )
	{
		for ( int i = 0; i < nodes.length; i++ )