}

  @SuppressWarnings("OptionalOfRedundantMethod") // Unit tests for Optional
  public void testOrNull_present() {
    assertThat(Optional.of("a").orNull()).isEqualTo("a");
  }

  public void testOrNull_absent() {
    assertThat(Optional.absent().orNull()).isNull();
  }

  public void testAsSet_present() {
    Set<String> expected = Collections.singleton("a");

      optionalSets.add(optionalSet);
    }
    Set<List<Optional<?>>> cartesianProduct = Sets.cartesianProduct(optionalSets);
    return Iterables.transform(cartesianProduct, objs -> Lists.transform(objs, Optional::orNull));
  }

  private CacheBuilder<Object, Object> createCacheBuilder(
      @Nullable Integer concurrencyLevel,
      @Nullable Integer initialCapacity,
      @Nullable Integer maximumSize,

val signArtifacts: Boolean = !pgpSigningKey.orNull.isNullOrEmpty()

tasks.withType<Sign>().configureEach { isEnabled = signArtifacts }

signing {
    useInMemoryPgpKeys(pgpSigningKey.orNull, pgpSigningPassPhrase.orNull)
    publishing.publications.configureEach {
        if (signArtifacts) {
            signing.sign(this)
        }
    }