Fix parsing of single-character string literals in JPQL and EQL collection member expressions.

[jewoodev]

JPQL and EQL currently tokenize a single-character quoted string such as 'c' as CHARACTER, while other quoted strings are tokenized as STRINGLITERAL. The literal parser rule accepted STRINGLITERAL but not CHARACTER, causing a single-character string literal to fail when used as the left operand of MEMBER OF.

This change adds CHARACTER to the JPQL and EQL literal rules and covers the collection-member case with a shared query renderer round-trip test.

Jakarta Persistence allows a literal as the left operand of MEMBER OF, defines string literals as single-quoted strings without distinguishing single-character strings from longer strings, and itself uses 'Joe' MEMBER OF p.nicknames as an example.

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See #4278

[mp911de]

Thanks a lot. Do you have a few more examples where the single-char case falls short? Also, getting an overview of unintentionally enabling functionality that wasn't previously possible (or breaking existing) would be great. We might want to introduce a bit more test coverage and cross-check whether we have similar issues in the HQL parser.

[jewoodev]

Thanks for the feedback.

I pushed additional TCK coverage for the same root cause in collection-member expressions: NOT MEMBER OF and the same MEMBER OF predicate inside subqueries, UPDATE where clauses, and DELETE where clauses.

I also found MEMBER without OF while probing. These cases fail in JPQL and EQL on main and pass with this branch. Other common single-character string literal positions such as comparisons, IN items, constructor arguments, LIKE, TRIM, FUNCTION, CASE, and UPDATE assignments already parse on main because they can route through string_expression/string_literal rather than literal.

I will follow up with the check for unintended enablement or breakage, and with the HQL parser cross-check.

[mp911de]

Alright, let me merge this PR. Once there is more, we can commit changes against the original bug report #4278

[mp911de]

Thank you for your contribution. That's merged and backported now.