Fix to SIMPLE_COLUMN resolution in HSQL parser

I don't actually understand how the circumstance arises that your new filter is causing to be handled differently --
a SIMPLE_COLUMN whose columnIndex matches that of another non-SIMPLE_COLUMN displayCol of type ExpressionColumn.

Looking at the particulars of the offending test case helps me NOT one bit, here.

A naive question is "Why is ExpressionColumn a special case? What assurance do I have that under some slightly altered circumstances I won't find a false positive match for some SIMPLE_COLUMN whose columnIndex matches that of some other type of non-SIMPLE_COLUMN in displayCols?
Your comment refers to columnIndex being context dependent. Is the ambiguity somehow only an issue for ExpressionColumn and not other Expression subtypes?