Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        existing = mergePlugin(existing, element, sourceDominant, context);
                        master.put(key, existing);
                        if (!pending.isEmpty()) {
                            predecessors.put(key, pending);

### New properties in an existing class

When adding a property to an existing class (task, extension, domain object, etc), the API should consist of managed lazy properties.  However, some exceptions need to be made to keep backwards compatibility with existing builds.

This is preferred when the implementation type is internal:

```groovy

                for (Plugin element : tgt) {
                    Object key = getPluginKey().apply(element);
                    Plugin existing = master.get(key);
                    if (existing != null) {
                        element = mergePlugin(element, existing, sourceDominant, context);

                        master.put(key, element);

                        if (!pending.isEmpty()) {

        return path;
    }

    public void merge(File existing, File result) throws RepositoryException {
        merge(existing != null ? existing.toPath() : null, result != null ? result.toPath() : null);
    }

    @Override
    public void merge(Path existing, Path result) throws RepositoryException {
        Metadata recessive = read(existing);

        merge(recessive);

        write(result, metadata);

	--remote-bucket http://minio:minio123@127.0.0.1:9004/bucket \
	--replicate "existing-objects,delete,delete-marker,replica-metadata-sync"
sleep 1

echo "adding replication rule for b -> a : ${remote_arn}"
./mc replicate add siteb/bucket/ \
	--remote-bucket http://minio:minio123@127.0.0.1:9001/bucket \
	--replicate "existing-objects,delete,delete-marker,replica-metadata-sync"
sleep 1

                Plugin existing = plugins.get(key);
                if (existing != null) {
                    if (version == null) {
                        version = existing.getVersion();
                    }
                    execs.addAll(existing.getExecutions());
                    deps.addAll(existing.getDependencies());
                }

    builder.addEscape(' ', "_");
    Escaper first = builder.build();
    // Modify one of the existing mappings before creating a new escaper.
    builder.addEscape(' ', "-");
    builder.addEscape('!', "$");
    Escaper second = builder.build();
    // This should have no effect on existing escapers.
    builder.addEscape(' ', "*");

    // Test both escapers after modifying the builder.

     */
    public void addProfile(Profile profile) {
        String profileId = profile.getId();

        Profile existing = profilesById.get(profileId);
        if (existing != null) {
            logger.warn("Overriding profile: '" + profileId + "' (source: " + existing.getSource()
                    + ") with new instance from source: " + profile.getSource());
        }

                for (PluginExecution element : tgt) {
                    Object key = getPluginExecutionKey().apply(element);
                    PluginExecution existing = merged.get(key);
                    if (existing != null) {
                        element = mergePluginExecution(element, existing, sourceDominant, context);
                    }
                    merged.put(key, element);
                }

    }
  }

  /**
   * Incorporate additional requirements into an existing requirements object.
   *
   * @param requirements the existing requirements object
   * @param moreRequirements more requirements to incorporate
   * @param source the source of the additional requirements (used only for error reporting)
   * @return the existing requirements object, modified to include the additional requirements