assertEquals( NotExpression.class, filPlan.getSources().get(0).getClass() );
NotExpression notExp = (NotExpression)filPlan.getSources().get(0);
assertTrue( ls.getField(0).uid != notExp.getFieldSchema().uid );
assertTrue( ls.getField(1).uid != notExp.getFieldSchema().uid );
assertEquals( IsNullExpression.class, notExp.getExpression().getClass() );
IsNullExpression isNull = (IsNullExpression)notExp.getExpression();
assertTrue( ls.getField(0).uid != isNull.getFieldSchema().uid );
assertTrue( ls.getField(1).uid != isNull.getFieldSchema().uid );
assertEquals( ProjectExpression.class, isNull.getExpression().getClass() );
ProjectExpression prj = (ProjectExpression) isNull.getExpression();
assertEquals( ls.getField(0).uid, prj.getFieldSchema().uid );
}