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 void checkDependencyCycle( ) throws DataException
	{
		List result = new ArrayList( );
		Iterator it = this.getColumnNames( ).iterator( );
		while ( it.hasNext( ) )
		{
			String name = it.next( ).toString( );
			Node n = new Node( name );
			IBaseExpression expr = exprManager.getExpr( name );
			if ( expr != null )
			{
				if ( !( expr instanceof IScriptExpression || expr instanceof IConditionalExpression ) )
				{
					throw new DataException( ResourceConstants.BAD_DATA_EXPRESSION );
				}
				List l = null;
				try
				{
					if ( expr instanceof IScriptExpression )
						l = ExpressionCompilerUtil.extractColumnExpression( (IScriptExpression) expr );
					else if ( expr instanceof IConditionalExpression )
						l = ExpressionCompilerUtil.extractColumnExpression( (IConditionalExpression) expr );
				}
				catch ( DataException e )
				{
					
					
				}