this.rootDirectory = rootDirectory;
            return this;
        }

        public ProtoSession build() {
            return new Impl(userProperties, systemProperties, startTime, topDirectory, rootDirectory);
        }

        private static class Impl implements ProtoSession {
            private final Map<String, String> userProperties;
            private final Map<String, String> systemProperties;

    protected List<Path> parseExtClasspath(C context) throws Exception {
        ProtoSession protoSession = context.protoSession;
        String extClassPath = protoSession.getUserProperties().get(Constants.MAVEN_EXT_CLASS_PATH);
        if (extClassPath == null) {
            extClassPath = protoSession.getSystemProperties().get(Constants.MAVEN_EXT_CLASS_PATH);
            if (extClassPath != null) {

            user.put(
                    "session.rootDirectory",
                    invokerRequest.rootDirectory().get().toString());
        }
        this.protoSession = ProtoSession.newBuilder()
                .withSystemProperties(invokerRequest.systemProperties())
                .withUserProperties(user)
                .withTopDirectory(invokerRequest.topDirectory())

    }

    @NotThreadSafe
    class ToolchainsBuilderRequestBuilder {
        ProtoSession session;
        RequestTrace trace;
        Source installationToolchainsSource;
        Source userToolchainsSource;

        public ToolchainsBuilderRequestBuilder session(ProtoSession session) {
            this.session = session;
            return this;
        }

    static SettingsBuilderRequest build(
            @Nonnull ProtoSession session,
            @Nonnull Source installationSettingsSource,
            @Nonnull Source userSettingsSource) {
        return build(session, installationSettingsSource, null, userSettingsSource);
    }

    @Nonnull
    static SettingsBuilderRequest build(

     *
     * @param <P> the type of problem
     * @param protoSession the session containing configuration for the problem collector
     * @return a new problem collector instance
     */
    @Nonnull
    static <P extends BuilderProblem> ProblemCollector<P> create(@Nullable ProtoSession protoSession) {
        if (protoSession != null
                && protoSession.getUserProperties().containsKey(Constants.MAVEN_BUILDER_MAX_PROBLEMS)) {

     *
     * @param protoSession The proto session, never {@code null}.
     * @return The user properties with contributions.
     */
    default Map<String, String> contribute(ProtoSession protoSession) {
        HashMap<String, String> userProperties = new HashMap<>(protoSession.getUserProperties());
        contribute(userProperties);
        return userProperties;
    }

     */
    protected void pushUserProperties(C context) throws Exception {
        ProtoSession protoSession = context.protoSession;
        HashSet<String> sys = new HashSet<>(protoSession.getSystemProperties().keySet());
        if (context.pushedUserProperties == null) {
            context.pushedUserProperties = new HashSet<>();
            protoSession.getUserProperties().entrySet().stream()

 *
 * @param <S> the type of ProtoSession associated with this request, allowing for
 *           type-safe session handling in specific request implementations
 *
 * @see ProtoSession
 * @see RequestTrace
 * @see Result
 * @since 4.0.0
 */
@Experimental
@Immutable
public interface Request<S extends ProtoSession> {

    /**
     * Returns the session associated with this request.

package org.apache.maven.api.services;

import org.apache.maven.api.ProtoSession;
import org.apache.maven.api.annotations.Experimental;
import org.apache.maven.api.annotations.Nonnull;

import static java.util.Objects.requireNonNull;

/**
 * Base class for requests.
 *
 * @since 4.0.0
 */
@Experimental
abstract class BaseRequest<S extends ProtoSession> implements Request<S> {

    private final S session;