Can't shutdown background threads [Firebase Admin SDK 4.1.5]

Running this on local machine with Java 8
` FirebaseOptions options = new FirebaseOptions.Builder()
.setCredential(FirebaseCredentials.applicationDefault())
.setDatabaseUrl("https://" + ServiceOptions.getDefaultProjectId() + ".firebaseio.com/")
.build();
`

`firebaseDatabase = FirebaseDatabase.getInstance(FirebaseApp.initializeApp(options));
final DatabaseReference entry = firebaseDatabase.getReference("somereference");
entry.setValue("data",(databaseError, databaseReference) -> System.out.println("ok"));`
How can i choose to use daemon threads? And if not, why don't you have a shutdown/close option?

I notice that entry.setValue("data") shutdowns threads normally.