*
 * @author Louis Wasserman
 */
@GwtCompatible
@ElementTypesAreNonnullByDefault
public class MoreCollectorsTest extends TestCase {
  public void testToOptionalEmpty() {
    assertThat(Stream.empty().collect(toOptional())).isEmpty();
  }

  public void testToOptionalSingleton() {
    assertThat(Stream.of(1).collect(toOptional())).hasValue(1);
  }

  public void testToOptionalNull() {

   * otherwise returns an empty stream.
   */
  public static <T> Stream<T> stream(com.google.common.base.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,
   * otherwise returns an empty stream.
   *

                    if (StringUtil.isNotEmpty(msg) || msg.contains("index.analyze.max_token_count")) {
                        logger.warn("Failed to parse document. ", e);
                        return Stream.empty();
                    }
                    throw e;
                }
            }).toArray(n -> new SuggestItem[n]);
            final long parseTime = System.currentTimeMillis();

    }
    Class<? extends T> implementation = getImplementation(type);
    if (implementation != null) {
      return get(implementation);
    }
    if (type == Stream.class) {
      return type.cast(Stream.empty());
    }
    if (type.isEnum()) {
      T[] enumConstants = type.getEnumConstants();
      return (enumConstants == null || enumConstants.length == 0) ? null : enumConstants[0];
    }
    if (type.isArray()) {

   * otherwise returns an empty stream.
   */
  public static <T> Stream<T> stream(com.google.common.base.Optional<T> optional) {
    return optional.isPresent() ? Stream.of(optional.get()) : Stream.empty();
  }

  /**
   * If a value is present in {@code optional}, returns a stream containing only that element,
   * otherwise returns an empty stream.
   *

                        Stream.of(new ProjectArtifact(project)),
                        // main project artifact if not a pom
                        "pom".equals(project.getPackaging()) ? Stream.empty() : Stream.of(project.getArtifact())),
                // attached artifacts
                project.getAttachedArtifacts().stream());
        return artifacts.map(RepositoryUtils::toArtifact);
    }

              }
            });
      }
    };
  }

  /**
   * Returns a fluent iterable containing no elements.
   *
   * <p><b>{@code Stream} equivalent:</b> {@code Stream.empty()}.
   *
   * @since 20.0
   */
  public static <E extends @Nullable Object> FluentIterable<E> of() {
    return FluentIterable.from(Collections.<E>emptyList());
  }

  /**

                    .orElse(false)) {
                return e.getValue().stream();
            }
            return Stream.empty();
        }).filter(StringUtil::isNotBlank).toArray(n -> new String[n]);
    }

    default void setAppValue(final String value) {
        setSystemProperty(Constants.APP_VALUE_PROPERTY, value);