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
if ( l != null )
				{
					for ( int j = 0; j < l.size( ); j++ )
					{
						n.addChild( new Node( l.get( j ) == null ? null
								: l.get( j ).toString( ) ) );
					}
				}
			}
			result.add( n );
		}
		Node[] source = new Node[result.size( )];
		for ( int i = 0; i < source.length; i++ )
		{
			source[i] = (Node) result.get( i );
		}
		validateNodes( source );
	}
	/**
	 * 
	 * @param source
	 * @return
	 * @throws DataException 
	 */
	private void validateNodes( Node[] source ) throws DataException
	{
		Node[] preparedNodes = populateNodeList( source );
		for ( int i = 0; i < preparedNodes.length; i++ )
		{
			isValidNode( preparedNodes[i], preparedNodes[i] );