MongoDB 3 brings a new authentication support SCRAM-SHA-1 and deprecated MONGODB-CR.
The support came with Java's driver 2.13 but requires some migrations https://github.com/mongodb/mongo-java-driver/releases/tag/r2.13.0
Upgrade to Java's driver 2.13
replace the default MongoDBProperties.AUTHENTICATION_MECHANISM from MONGODB-CR to SCRAM-SHA-1 (and add the latter in AuthenticationMechanismType)
write in the migration guide how to explicitly set the auth mechanism for people with older MongoDB databases
Change to use MongoCredential.html#createCredential instead of MongoCredential#createMongoCRCredential
That should do the trick.
The workaround according to Dean is to do