import org.apache.maven.api.annotations.ThreadSafe;

/**
 * A container for data that is specific to a session.
 * All components may use this storage to associate arbitrary data with a session.
 * <p>
 * Unlike a cache, this session data is not subject to purging. For this same reason, session data should also not be
 * abused as a cache (i.e. for storing values that can be re-calculated) to avoid memory exhaustion.

import org.apache.maven.api.services.ModelBuilderRequest;
import org.apache.maven.api.services.ModelProblemCollector;
import org.apache.maven.api.services.model.ModelBuildingEvent;

/**
 * Holds data relevant for a model building event.
 */
record DefaultModelBuildingEvent(
        Model model, Consumer<Model> update, ModelBuilderRequest request, ModelProblemCollector problems)

            mojos.remove(Thread.currentThread());
        }

        private OwnerReentrantLock getProjectLock(MavenSession session) {
            SessionData data = session.getSession().getData();
            Map<MavenProject, OwnerReentrantLock> locks = data.computeIfAbsent(PROJECT_LOCKS, ConcurrentHashMap::new);
            return locks.computeIfAbsent(session.getCurrentProject(), p -> new OwnerReentrantLock());
        }
    }

    // The expressions help a lot, but we need a clean to pick up a directory of POMs, automatically load
    // them into a resolver, create the expression to extract the data to validate the Model, and the URI
    // to validate the properties. We also need a way to navigate from the Tex specification documents to
    // the test in question and vice versa. A little Eclipse plugin would do the trick.

        }
    }

    @Override
    public Map<ChecksumAlgorithm, String> calculate(byte[] data, Collection<ChecksumAlgorithm> algorithms) {
        nonNull(data, "data");
        nonNull(algorithms, "algorithms");
        try {
            return calculate(new ByteArrayInputStream(data), algorithms);
        } catch (IOException e) {
            throw new UncheckedIOException(e); // really unexpected
        }

        }
    }

    @Override
    public Map<ChecksumAlgorithm, String> calculate(byte[] data, Collection<ChecksumAlgorithm> algorithms) {
        nonNull(data, "data");
        nonNull(algorithms, "algorithms");
        try {
            return calculate(new ByteArrayInputStream(data), algorithms);
        } catch (IOException e) {
            throw new UncheckedIOException(e); // really unexpected
        }

 * identity of a model. The tag allows for further classification of the associated data on the sole discretion of the
 * model builder.
 *
 */
public interface ModelCache {

    <T> T computeIfAbsent(String groupId, String artifactId, String version, String tag, Supplier<T> data);

    <T> T computeIfAbsent(Source path, String tag, Supplier<T> data);

        return session;
    }

    private static final char[] hexCode = "0123456789ABCDEF".toCharArray();

    private static String printHexBinary(byte[] data) {
        StringBuilder r = new StringBuilder(data.length * 2);
        for (byte b : data) {
            r.append(hexCode[(b >> 4) & 0xF]);
            r.append(hexCode[(b & 0xF)]);
        }
        return r.toString();
    }

        return (T) computeIfAbsent(new GavCacheKey(groupId, artifactId, version, tag), data);
    }

    @Override
    @SuppressWarnings({"unchecked"})
    public <T> T computeIfAbsent(Source path, String tag, Supplier<T> data) {
        return (T) computeIfAbsent(new SourceCacheKey(path, tag), data);
    }

     */
    @Nonnull
    Map<ChecksumAlgorithm, String> calculate(@Nonnull byte[] data, @Nonnull Collection<ChecksumAlgorithm> algorithms);

    /**
     * Calculates checksums for specified data.
     *
     * @param data        The content for which to calculate checksums, must not be {@code null}.
     * @param algorithms  The checksum algorithms to use, must not be {@code null}.