Partial key search error

[ArtDu]

Partial search does not work with multipart index. Since null is serialized to box.NULL.

repro:

Optional<?> findResponse = repository.findById(
                ClientChannelId.builder()
                        .mdmId(1)
                        .build());

or

Optional<?> findResponse = repository.findById(
                ClientChannelId.builder()
                        .mdmId(1)
                        .channelType(null)
                        .build());

org.springframework.dao.DataRetrievalFailureException: InnerErrorMessage:
str: SelectError: Supplied key type of part 1 does not match index part type: expected string