lookup_equijoin_semantics_lib.js currently tests NLJ, HJ, INLJ (ascending/descending), hashed INLJ, and Sparse_Asc. There is no coverage for the collation-mismatch DILJ path, which is the other reason DILJ can be chosen. A new JoinAlgorithm entry (e.g. DILJ_CollationMismatch) should be added and a corresponding test file should exercise the full null/missing/array/nested-path semantics matrix against an index with an incompatible collation, matching the coverage level of lookup_equijoin_semantics_sparse.js