I'm writing a FilterableTable implementation and so far all is well. When
handling more complex filters I've come across the need to pass in a boolean
flag via a filter clause, something like:
select "foo" from "bar" where "clean"=true and "id"='1234'
This results in a filter like: AND(CAST($2):BOOLEAN, =(CAST($0):VARCHAR,
'1234')), and I'm trying to figure out how to get to the actual value used for
the boolean. The operand in this case is a RexInputRef from which I can get to
the RelDataTypeField but I can't find the literal anywhere. Any guidance here?
