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
}
				throw new DataException( ResourceConstants.INVALID_GROUP_KEY, new Object[]{ map.get( level ).toString( ), level});
			}
		}
		exprManager.setEntryGroupLevel( ExprManager.OVERALL_GROUP );
	}
	
	/**
	 * 
	 * @param columnName
	 * @return
	 */
	private boolean isColumnBindingExist( String columnName )
	{
		List bindings = exprManager.getBindingExprs( );
		
		for( int i = 0; i < bindings.size( ); i++ )
		{
			GroupBindingColumn gbc = (GroupBindingColumn)bindings.get( i );
			if(gbc.getExpression( columnName) != null)
				return true;
		}
		return false;
	}
	/**
	 * Test whether there are dependency cycles in exprManager.
	 * 
	 * @param exprManager
	 * @return
	 * @throws DataException