Android soft input - getting new line character when clicking 'done'

Question

There is strange problem that I have come across, I have EditText like this

<EditText
        android:id="@+id/pin_digit"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:inputType="numberPassword"
        android:selectAllOnFocus="true"
        android:maxLength="1"/>

And in some activity code used with ButterKnife (version 6.1.0),

@OnTextChanged(R.id.pin_digit)
    public void onPinTextChanged(CharSequence sequence){
        //do something with sequence
    }

My problem is that, when I type (on softinput) a digit, everything is ok, but when i click "done" this event is triggered with new line character (softinput is of course hidden properly), but i get invalid character in my input.

Have you ever encountered something like this?

I have solved this one tempolary by checking if inputed char sequence is ineed a digit, but I would like to solve a real problem, not heal the results...