OptionalEntity<String> stringOpt = OptionalUtil.ofNullable("string");
        OptionalEntity<Integer> intOpt = OptionalUtil.ofNullable(42);
        OptionalEntity<Boolean> boolOpt = OptionalUtil.ofNullable(true);
        OptionalEntity<Date> dateOpt = OptionalUtil.ofNullable(new Date());

        assertTrue(stringOpt.isPresent());
        assertTrue(intOpt.isPresent());

                .filter(StringUtil::isNotBlank)
                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrTelephoneNumber(), s)));
        OptionalUtil.ofNullable(user.getHomePhone())
                .filter(StringUtil::isNotBlank)
                .ifPresent(s -> entry.put(new BasicAttribute(fessConfig.getLdapAttrHomePhone(), s)));

        return Optional.ofNullable(parserRequest().stdIn());
    }

    /**
     * Returns the output stream for the Maven execution, if running in embedded mode.
     *
     * @return an {@link Optional} containing the output stream, or empty if not applicable
     */
    @Nonnull
    default Optional<OutputStream> stdOut() {
        return Optional.ofNullable(parserRequest().stdOut());
    }

            public Optional<Source> getInstallationSettingsSource() {
                return Optional.ofNullable(installationSettingsSource);
            }

            @Nonnull
            @Override
            public Optional<Source> getProjectSettingsSource() {
                return Optional.ofNullable(projectSettingsSource);
            }

            @Nonnull
            @Override

     *
     * @param <T> the type of the entity
     * @param entity the entity (can be null)
     * @return the OptionalEntity
     */
    public static <T> OptionalEntity<T> ofNullable(final T entity) {
        return OptionalEntity.ofNullable(entity, () -> {});
    }

            public Optional<Source> getInstallationToolchainsSource() {
                return Optional.ofNullable(installationToolchainsSource);
            }

            @Nonnull
            @Override
            public Optional<Source> getUserToolchainsSource() {
                return Optional.ofNullable(userToolchainsSource);
            }

            @Override
            public boolean equals(Object o) {

            @Nonnull
            @Override
            public Optional<Project> getProject() {
                return Optional.ofNullable(project);
            }

            @Nonnull
            @Override
            public Optional<Artifact> getRootArtifact() {
                return Optional.ofNullable(rootArtifact);
            }

            @Nonnull
            @Override

            @Nonnull
            @Override
            public Optional<Path> getPath() {
                return Optional.ofNullable(path);
            }

            @Nonnull
            @Override
            public Optional<Source> getSource() {
                return Optional.ofNullable(source);
            }

            @Override
            public boolean isAllowStubModel() {

                                    path = defaultArtifact.getArtifact().getPath();
                                }
                                return Optional.ofNullable(path);
                            }

                            @Override
                            public void setPath(ProducedArtifact artifact, Path path) {

          throw multiples(true);
        }
        return this;
      }
    }

    Optional<Object> getOptional() {
      if (extras.isEmpty()) {
        return Optional.ofNullable(element);
      } else {
        throw multiples(false);
      }
    }

    Object getElement() {
      if (element == null) {
        throw new NoSuchElementException();