return md == null ? "no metadata" : md.toString();
    }

    // ------------------------------------------------------------------
    public String graphHash() throws MetadataResolutionException {
        if (md == null) {
            throw new MetadataResolutionException(
                    "treenode without metadata, parent: " + (parent == null ? "null" : parent.toString()));
        }

        Objects.requireNonNull(output, "output cannot be null");
        Objects.requireNonNull(toolchains, "toolchains cannot be null");

        try (Writer out = output) {
            new MavenToolchainsStaxWriter().write(out, toolchains.getDelegate());
        } catch (XMLStreamException e) {
            throw new IOException("Error writing toolchains", e);
        }

            @Override
            public int read(char[] cbuf, int off, int len) throws IOException {
                if (delegate == null) {
                    delegate = transform(original);
                }
                return delegate.read(cbuf, off, len);
            }

            @Override
            public void close() throws IOException {
                if (delegate != null) {
                    delegate.close();

    @Override
    public Object invoke(Object target, Method method, Object[] args) throws Throwable {
      assertTrue("setUp should have run", setUpRan.get());
      try {
        return method.invoke(map, args);
      } catch (InvocationTargetException e) {
        throw e.getCause();
      } catch (IllegalAccessException e) {
        throw newLinkageError(e);
      }
    }
  }

    }
  }

  /**
   * Checks if the executor has been shut down and increments the running task count.
   *
   * @throws RejectedExecutionException if the executor has been previously shutdown
   */
  private void startTask() {
    synchronized (lock) {
      if (shutdown) {
        throw new RejectedExecutionException("Executor already shutdown");
      }
      runningTasks++;
    }
  }

    }

    return new FilteredCollection<>(checkNotNull(unfiltered), checkNotNull(predicate));
  }

  /**
   * Delegates to {@link Collection#contains}. Returns {@code false} if the {@code contains} method
   * throws a {@code ClassCastException} or {@code NullPointerException}.
   */
  static boolean safeContains(Collection<?> collection, @Nullable Object object) {
    checkNotNull(collection);
    try {

  /**
   * @throws IllegalArgumentException if another entry in the bucket has the same key
   * @throws BucketOverflowException if this bucket has too many entries, which may indicate a hash
   *     flooding attack
   */
  private static void checkNoConflictInValueBucket(
      Object value, Entry<?, ?> entry, @Nullable ImmutableMapEntry<?, ?> valueBucketHead)
      throws BucketOverflowException {

                            splitExpr = ">";
                        } else {
                            throw new IllegalArgumentException("Unrecognized entry: " + l);
                        }
                        String[] parts = l.split(splitExpr);
                        if (parts.length < 1) {
                            throw new IllegalArgumentException("Unrecognized entry: " + l);
                        }

  }

  Object writeReplace() {
    return new SerializedForm(prototype.getAlgorithm(), bytes, toString);
  }

  private void readObject(ObjectInputStream stream) throws InvalidObjectException {
    throw new InvalidObjectException("Use SerializedForm");
  }

  /** Hasher that updates a message digest. */
  private static final class MessageDigestHasher extends AbstractByteHasher {

    /**
     * @param parameter add a new parameter
     * @throws DuplicateParameterException if any
     */
    public void addParameter(Parameter parameter) throws DuplicateParameterException {
        if (parameters.contains(parameter)) {
            throw new DuplicateParameterException(parameter.getName()
                    + " has been declared multiple times in mojo with goal: " + getGoal() + " (implementation: "