code: public static Validator<CharSequence> equal(@NonNull final CharSequence errorMessage,
                                                  @NonNull final EditText editText) {
          return new EqualValidator(errorMessage, editText);
      }
docs: Creates and returns a validator, which allows to validate texts to ensure, that they are
  equal to the text, which is contained by an {@link EditText} widget.
  
  @param errorMessage
  The error message, which should be shown, if the validation fails, as an instance of
  the type {@link CharSequence}. The error message may not be null
  @param editText
  The edit text widget, which contains the content, the texts should be equal to, as an
  instance of the class {@link EditText}. The widget may not be null
  @return The validator, which has been created, as an instance of the type {@link Validator}