code: private void initializePreferenceInitialFragmentButton() {
          Button preferenceInitialFragmentButton =
                  findViewById(R.id.preference_initial_fragment_button);
          preferenceInitialFragmentButton
                  .setOnClickListener(createPreferenceInitialFragmentButtonListener());
      }
docs: Initializes the button, which allows to show a specific header of a {@link
  PreferenceActivity}.