Firebase – How to update user data without changes into Firestore when it's checking for already existence in database?

I recently implemented unique username into my app when registering, all good far here, by the way I also need to set it to when the user is editting it’s profile.

I tried to do the same thing, but I’m facing an issue here. The app don’t let save the profile, because it’s checking if the username’s taken and, as we’re already using one, it won’t let us do it.

Ex.: My username is "bob", I changed my profile pic or my display name, so when I click to save, the app will do a username checking in the background and will not let me save it because the username is already taken, but the problem is that it’s already my user.

I’ve tried to set this, but failed:

if (document.equals(setup_username.getText().toString()) || document.isEmpty()){
    updateProfile();

Here’s my code:

setup_progressbar.setVisibility(View.VISIBLE);
FirebaseFirestore.getInstance().collection("Users").whereEqualTo("username",setup_username.getText().toString()).get().addOnCompleteListener((task) -> {
    if (task.isSuccessful()){
        List<DocumentSnapshot> document = task.getResult().getDocuments();
        if (document.equals(setup_username.getText().toString()) || document.isEmpty()){
            updateProfile();
        } else {
            setup_progressbar.setVisibility(View.INVISIBLE);
            setup_username.setError(getString(R.string.username_taken));
            return;
        }
    } else {
        setup_progressbar.setVisibility(View.INVISIBLE);
        String error = task.getException().getMessage();
        FancyToast.makeText(getApplicationContext(), error, FancyToast.LENGTH_SHORT, FancyToast.ERROR, false).show();
    }
});

So how to get around this and only forbid it when I try to change my username to another that is taken? Like: "bob" to "bill", but "bill" is already taken, so it won’t allow.