AUTH plugins cannot be built statically as documented

I maintain the R bindings for mariadb-connector-c. I need to build a version of libmariadbclient for MacOS with only static plugins. This does not work (at least not as documented).

Accoring to the documentation it should be possible to:

cmake .. -DCLIENT_PLUGIN_{PLUGIN_NAME}=[STATIC|DYNAMIC|OFF]

However when I try this cmake says the following:

   CMake Warning:

      Manually-specified variables were not used by the project:

    CLIENT_PLUGIN_AUTH_GSSAPI

And it still builds the following plugins as shared libraries:

auth_gssapi_client.so		client_ed25519.so		remote_io.so

caching_sha2_password.so	mysql_clear_password.so

I also noticed that the documentation says that the CMAKE parameter AUTH_GSSAPI_PLUGIN_TYPE was recently renamed to CLIENT_PLUGIN_AUTH_GSSAPI, however the top level CMakeLists.txt still contains some reference to AUTH_GSSAPI_PLUGIN_TYPE, so perhaps that is the problem?