public static Builder newBuilder(String rootLoggerName) {
    return new Builder(rootLoggerName);
  }
@Test
  public void newBuilder_throws_NPE_if_rootLoggerName_is_null() {
    assertThatThrownBy(() -> newBuilder(null))
      .isInstanceOf(NullPointerException.class)
      .hasMessage("rootLoggerName can't be null");
  }