}

    private void addMojoExecution(
            Map<PhaseId, List<MojoExecution>> phaseBindings, MojoExecution mojoExecution, PhaseId phaseId) {
        List<MojoExecution> mojoExecutions = phaseBindings.computeIfAbsent(phaseId, k -> new ArrayList<>());

        mojoExecutions.add(mojoExecution);
    }

     * @param supplier the supplier will compute the new value
     * @return the session data associated with the key
     */
    @Nullable
    <T> T computeIfAbsent(@Nonnull Key<T> key, @Nonnull Supplier<T> supplier);

    /**
     * Create a key using the given class as an identifier and as the type of the object.
     */
    static <T> Key<T> key(Class<T> clazz) {

            throw uoe();
        }

        @Override
        public V replace(K key, V value) {
            throw uoe();
        }

        @Override
        public V computeIfAbsent(K key, Function<? super K, ? extends V> mappingFunction) {
            throw uoe();
        }

        @Override

            }
        }
        return Language.UNKNOWN;
    }

    private static void addError(Map<File, List<Error>> errors, File file, Error error) {
        errors.computeIfAbsent(file, f -> new ArrayList<>()).add(error);
    }

    private enum Language { KOTLIN, GROOVY, UNKNOWN }

    private static final class Snippet {

    }

    @Override
    public Project getProject(MavenProject project) {
        return project != null && project.getBasedir() != null
                ? allProjects.computeIfAbsent(project.getId(), id -> new DefaultProject(this, project))
                : null;
    }

    @Override
    public List<ArtifactRepository> toArtifactRepositories(List<RemoteRepository> repositories) {

            }

            if (cls.isArray()) {
                evaluateArray(target);
            } else if (isQualifiedForInterpolation(cls)) {
                Field[] fields = FIELDS_BY_CLASS.computeIfAbsent(cls, k -> cls.getDeclaredFields());

                for (Field field : fields) {
                    Class<?> type = field.getType();
                    if (isQualifiedForInterpolation(field, type)) {

            }

            String projectKey = ArtifactUtils.versionlessKey(project.getGroupId(), project.getArtifactId());

            Map<String, Vertex> vertices = vertexMap.computeIfAbsent(projectKey, k -> new HashMap<>(2, 1));

            vertices.put(project.getVersion(), graph.addVertex(projectId));
        }

        for (Vertex projectVertex : graph.getVertices()) {

            gasLocations.computeIfAbsent(ga, k -> new ArrayList<>()).add(location);
            // TODO: metaversions could be extensible enum with these two values out of the box
            if ("LATEST".equals(coreExtension.getVersion()) || "RELEASE".equals(coreExtension.getVersion())) {
                metaVersionLocations.computeIfAbsent(ga, k -> new ArrayList<>()).add(location);
            }
        }

        SessionData data = request.getRepositorySession().getData();
        return (ConcurrentMap<Key, PluginVersionResult>)
                data.computeIfAbsent(CACHE_KEY, () -> new ConcurrentHashMap<>(256));
    }

    private static Key getKey(PluginVersionRequest request) {
        return new Key(request.getGroupId(), request.getArtifactId(), request.getRepositories());

        override fun <T> tag(type: Class<out T>): T? = TODO()

        override fun <T : Any> tag(
          type: KClass<T>,
          computeIfAbsent: () -> T,
        ): T = TODO()

        override fun <T : Any> tag(
          type: Class<T>,
          computeIfAbsent: () -> T,
        ): T = TODO()

        override fun clone(): Call = TODO()
      }
  }

  @Test
  fun callback() {