DDC-3065 - failing test - IN()-alike criteria should support NULL search values
DDC-3065 - hardening test - should support multiple values in IN(), also NULL ones
DDC-3065 - splitting tests and checking multiple values support
DDC-3065 - persister tests for criteria containing `NULL` values in `IN()` conditions
DDC-3065 - applying hotfix that allows `NULL` in `IN()` criteria
Merge pull request #999 from doctrine/hotfix/DDC-3065-null-value-in-in-criteria-support

DDC-3065 null value in in criteria support
DDC-3085 Verify ResultVariable works in combination with NullComparisonExpression wihle in HAVING clause.