public Collection<CachingProvider<?>> providers() {
            return provided.values();
        }
    }

    private final List<ScopeState> values = new CopyOnWriteArrayList<>();

    public void enter() {
        values.add(0, new ScopeState());
    }

    protected ScopeState getScopeState() {
        if (values.isEmpty()) {

                    T extends ExtensibleEnum, P extends ExtensibleEnumProvider<T>>
            implements ExtensibleEnumRegistry<T> {

        protected final Map<String, T> values;

        DefaultExtensibleEnumRegistry(List<P> providers, T... builtinValues) {
            values = Stream.<T>concat(
                            Stream.of(builtinValues), providers.stream().flatMap(p -> p.provides().stream()))

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

/**
 * Replaces expressions of the form <code>${token}</code> with their effective values. Effective values are basically
 * calculated from the elements of the model itself and the execution properties from the building request.
 *
 */
public interface ModelInterpolator {

    /**

     * It may however contain more than one entry if module hierarchy was detected,
     * in which case there is one key per sub-directory.
     *
     * <p>This map may contain null values if the constructor was invoked with {@code resolve}
     * parameter set to false. This is more efficient when only the module existence needs to
     * be tested, and module descriptors are not needed.</p>
     *

                if (!merged.containsKey(key)) {
                    merged.put(key, element);
                }
            }

            builder.repositories(merged.values());
        }
    }

    @Override
    protected void mergeModelBase_PluginRepositories(
            ModelBase.Builder builder,
            ModelBase target,
            ModelBase source,

    /**
     * Injects the mirroring information into the specified repositories. For each repository that is matched by a
     * mirror, its URL and ID will be updated to match the values from the mirror specification. Repositories without a
     * matching mirror will pass through unchanged. Note: This method must be called before

 *
 * @param <T> The type of extensible enum to extend
 */
@Experimental
@Consumer
public interface ExtensibleEnumProvider<T extends ExtensibleEnum> extends SpiService {

    /**
     * Registers new values for the T extensible enum.
     *
     * @return a collection of T instances to register
     */
    @Nonnull
    Collection<T> provides();

                    snapshots.put(key, snapshotMetadata);
                }
                snapshotMetadata.bind(artifact);
            }
        }

        return snapshots.values();
    }

    @Override
    public Artifact transformArtifact(Artifact artifact) {
        if (artifact.isSnapshot() && artifact.getVersion().equals(artifact.getBaseVersion())) {

                    }
                    merged.put(key, element);
                }

                builder.executions(merged.values());
            }
        }
    }

     */
    @Nonnull
    String getLocation();

    /**
     * Returns a new source identified by a relative path. Implementation <strong>MUST</strong>
     * be able to accept <code>relative</code> parameter values that
     * <ul>
     * <li>use either / or \ file path separator,</li>
     * <li>have .. parent directory references,</li>
     * <li>point either at file or directory.</li>
     * </ul>
     *