code: @NonNull
      private View.OnFocusChangeListener createFocusChangeListener() {
          return new View.OnFocusChangeListener() {
  
              @Override
              public void onFocusChange(final View v, final boolean hasFocus) {
                  if (!hasFocus && validateOnFocusLost) {
                      validate();
                  }
              }
  
          };
      }
docs: Creates and returns a listener, which allows to validate the dialog's edit text widget when
  its focus got lost.
  
  @return The listener, which has been created, as an instance of the type {@link
  View.OnFocusChangeListener}. The listener may not be null