the MongoDB cachestore has not been upgraded to the Infinispan 6+ SPI, so that would need to happen.
Recently the Cassandra store has received such treatment and we are in the process of integrating it in server. The Redis store is also ready for such integration. If you are interested in helping out with the MongoDB store, please let me know.
If you have no particular expectations I could try to help in best effort.
Can we try?
You should use the new Cassandra Cache Store  or the Redis Cache Store  as a starting point.