@Override
  public String getRawSourceHash(Component file) {
    checkComponentArgument(file);
    if (rawSourceHashesByKey.containsKey(file.getKey())) {
      return checkSourceHash(file.getKey(), rawSourceHashesByKey.get(file.getKey()));
    } else {
      String newSourceHash = computeRawSourceHash(file);
      rawSourceHashesByKey.put(file.getKey(), newSourceHash);
      return checkSourceHash(file.getKey(), newSourceHash);
    }
  }
@Test
  void getRawSourceHash_throws_NPE_if_Component_argument_is_null() {
    assertThatThrownBy(() -> underTest.getRawSourceHash(null))
      .isInstanceOf(NullPointerException.class)
      .hasMessage("Specified component can not be null");
  }