@Override
  protected void set(String key, String value) {
    props.put(
      requireNonNull(key, "key can't be null"),
      requireNonNull(value, "value can't be null").trim());
  }
@Test
  public void set_accepts_empty_value_and_trims_it() {
    MapSettings underTest = new MapSettings();
    Random random = new Random();
    String key = randomAlphanumeric(3);

    underTest.set(key, blank(random));

    assertThat(underTest.getString(key)).isEmpty();
  }