/**
 * The session to install / deploy / resolve artifacts and dependencies.
 *
 * TODO: move the remote repositories in the requests (plugins will need to access this list somehow)
 * TODO: add request trace so that requests can be linked together and through the resolver
 * TODO: add a Request interface holding session + parent request
 *
 * @since 4.0.0
 */
@Experimental
@ThreadSafe
public interface Session {

            RequestTrace trace,
            RepositorySystem resolver,
            RemoteRepositoryManager remoteRepositoryManager,
            List<RemoteRepository> repositories,
            ProjectBuildingRequest.RepositoryMerging repositoryMerging,
            ReactorModelPool modelPool,
            Map<String, Object> parentCache) {
        this.session = session;
        this.trace = trace;
        this.resolver = resolver;

    @Override
    public void flush() {
        cache.clear();
    }

    @Override
    public void register(MavenProject project, Key cacheKey, CacheRecord record) {
        // default cache does not track record usage
    }

 */
public interface MessageBuilder extends Appendable {

    /**
     * Append message content in trace style.
     * By default, bold magenta
     *
     * @param message the message to append
     * @return the current builder
     */
    @Nonnull
    default MessageBuilder trace(Object message) {
        return style(".trace:-bold,f:magenta", message);
    }

    /**
     * Append message content in debug style.

            ModelBuilderRequest.ModelBuilderRequestBuilder modelBuildingRequest = ModelBuilderRequest.builder();

            RequestTrace trace = RequestTrace.newChild(null, request).newChild(modelBuildingRequest);

            ModelResolver resolver = new ModelResolverWrapper() {
                @Override

            RepositorySystemSession session,
            RequestTrace trace,
            Metadata metadata,
            ArtifactRepository repository,
            Exception exception) {
        RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.METADATA_INVALID);
        event.setTrace(trace);
        event.setMetadata(metadata);
        event.setException(exception);

                request.addDependency(pluginDep);
            }

            DependencyRequest depRequest = new DependencyRequest(request, resolutionFilter);
            depRequest.setTrace(trace);

            request.setTrace(RequestTrace.newChild(trace, depRequest));

            node = repoSystem.collectDependencies(pluginSession, request).getRoot();

            if (logger.isDebugEnabled()) {

        } catch (Exception e) {
            invalidMetadata(session, trace, metadata, repository, e);
            result.addException(e);
        }

        return (versioning != null) ? versioning : Versioning.newInstance();
    }

    private void invalidMetadata(
            RepositorySystemSession session,
            RequestTrace trace,
            Metadata metadata,
            ArtifactRepository repository,

     *
     * @param content
     * @param error
     */
    void debug(CharSequence content, Throwable error);

    /**
     * Send an exception to the user in the <b>debug</b> error level.<br>
     * The stack trace for this exception will be output when this error level is enabled.
     *
     * @param error
     */
    void debug(Throwable error);

    void debug(Supplier<String> content);

        return result;
    }

    private void missingDescriptor(
            RepositorySystemSession session, RequestTrace trace, Artifact artifact, Exception exception) {
        RepositoryEvent.Builder event = new RepositoryEvent.Builder(session, EventType.ARTIFACT_DESCRIPTOR_MISSING);
        event.setTrace(trace);
        event.setArtifact(artifact);
        event.setException(exception);