private static Map<String, String> createUserDatabase() {
    Map<String, String> db = new ConcurrentHashMap<>();
    db.put("user1", USER1_PASSWORD);
    db.put("user2", USER2_PASSWORD);
    return db;
  }
Tests the pluggable authentication framework with SASL using a contrived authentication system.
This tests holds a "user database" in memory as a hashmap. Clients provide their password in the
client Hadoop configuration. The servers validate this password via the "user database".
hbase-server/src/test/java/org/apache/hadoop/hbase/security/provider/CustomSaslAuthenticationProviderTestBase.java