public Optional<UpdateCenter> getUpdateCenter() {
    return getUpdateCenter(false);
  }
@Test
  public void forceRefresh() throws Exception {
    when(reader.readString(new URI(URL_DEFAULT_VALUE), StandardCharsets.UTF_8)).thenReturn("sonar.versions=2.2,2.3");

    underTest.getUpdateCenter();
    underTest.getUpdateCenter(true);

    verify(reader, times(2)).readString(new URI(URL_DEFAULT_VALUE), StandardCharsets.UTF_8);
  }