Hello.
I made authentication by different ways for our product (REST API, Thrift API) with Spring Security. It's supports such authentication methods like BASIC, DIGEST-MD5, Negotiate/NTLM via highly customizable waffle (allow Single Sign-On for web). Also I worked last 3 years with Cassandra and have experience with reactive programming in Scala. I don't worked with Neo4j, but we used OrientDB, other graph database.
I can provide github with student time examples of code in chat.