@Override
  public void onProjectsRekeyed(Set<RekeyedProject> rekeyedProjects) {
    checkNotNull(rekeyedProjects, "rekeyedProjects can't be null");
    if (rekeyedProjects.isEmpty()) {
      return;
    }

    Arrays.stream(listeners)
      .forEach(safelyCallListener(listener -> listener.onProjectsRekeyed(rekeyedProjects)));
  }
@Test
  public void onProjectsRekeyed_throws_NPE_if_set_is_null() {
    assertThatThrownBy(() -> underTestWithListeners.onProjectsRekeyed(null))
      .isInstanceOf(NullPointerException.class)
      .hasMessage("rekeyedProjects can't be null");
  }