String SERVER_NAME = "<hostName>";
    System.setProperty("java.security.krb5.conf", "path\to\krb5.conf");
    System.setProperty("java.security.krb5.realm", "Domain.COM");
    System.setProperty("java.security.krb5.kdc", "kdc.domain.com");
    System.setProperty("javax.security.auth.useSubjectCredsOnly", "false");
    System.setProperty("java.security.auth.login.config","path\to\jaas.config");
    MongoCredential credential = MongoCredential.createGSSAPICredential("user@domain.COM");
    ServerAddress serverAddress = new ServerAddress(SERVER_NAME+".domain.com", 20203);
    mongoClient = new MongoClient(serverAddress, Arrays.asList(credential));