}
	for k, v := range d.Cache {
		clone.Cache[k] = v.clone()
	}
	return clone
}

// merge root of other into d.
// children of root will be flattened before being merged.
// Last update time will be set to the last updated.
func (d *dataUsageCache) merge(other dataUsageCache) {
	existingRoot := d.root()
	otherRoot := other.root()
	if existingRoot == nil && otherRoot == nil {
		return

    /**
     * Merges the specified source object into the given target object.
     *
     * @param target The target object whose existing contents should be merged with the source, must not be
     *            <code>null</code>.
     * @param source The (read-only) source object that should be merged into the target object, may be
     *            <code>null</code>.

            Map<String, String> merged = new HashMap<>();
            if (sourceDominant) {
                merged.putAll(target.getProperties());
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
            } else {
                putAll(merged, source.getProperties(), CHILD_DIRECTORY_PROPERTY);
                merged.putAll(target.getProperties());
            }

                    PluginExecution existing = merged.get(key);
                    if (existing != null) {
                        element = mergePluginExecution(existing, element, sourceDominant, context);
                    }
                    merged.put(key, element);
                }

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

        @Override

                    PluginExecution existing = merged.get(key);
                    if (existing != null) {
                        element = mergePluginExecution(element, existing, sourceDominant, context);
                    }
                    merged.put(key, element);
                }

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

                    if (dependency != null) {
                        Dependency merged = mergeDependency(dependency, managedDependency, false, context);
                        if (merged != dependency) {
                            dependencies.put(key, merged);
                            modified = true;
                        }
                    }
                }

class MavenToolchainMergerTest {
    private MavenToolchainMerger merger = new MavenToolchainMerger();

    private DefaultToolchainsReader reader = new DefaultToolchainsReader();

    @Test
    void testMergeNulls() {
        merger.merge(null, null, null);

        PersistedToolchains pt = new PersistedToolchains();
        merger.merge(pt, null, null);
        merger.merge(null, pt, null);
    }

    @Test

        Model source = Model.newBuilder().artifactId("SOURCE").build();

        Model merged = mavenMerger.merge(target, source, true, null);
        assertThat(merged.getArtifactId(), is("SOURCE"));

        merged = mavenMerger.merge(target, source, false, null);
        assertThat(merged.getArtifactId(), is("TARGET"));
    }

    @Test
    void mergeSameContributors() {
        Contributor contributor =

        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);

@Deprecated(since = "4.0.0")
public interface ProfileInjector {

    /**
     * Merges values from the specified profile into the given model. Implementations are expected to keep the profile
     * and model completely decoupled by injecting deep copies rather than the original objects from the profile.
     *
     * @param model The model into which to merge the values defined by the profile, must not be <code>null</code>.