Automatic CASE WHEN wrapping of boolean expressions

[Mobe91]

We should add support for plain boolean expressions in entity view mappings like e.g.:

@Mapping("age > 10")

Since JPQL does not support plain boolean expressions in select items, the user currently needs to manually formulate such mappings as CASE WHEN:

@Mapping("CASE WHEN age > 10 THEN true ELSE false END")

This CASE WHEN wrapping should happen automatically.

[beikov]

Actually I think we should do this in core already instead. Entity views should not have to change anything and only the final JPQL output should show the transformed expression.

[Mobe91]

Maybe we can also allow boolean expressions such as x OR y without having to write x = true OR y = true.

[jwgmeligmeyling]

Although well aware of this limitation, I recently stumbled upon this again by surprise with a x IN (subquery) expression and a SUM(x) IS NOT NULL NULL expression in the select clause.