}
	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

    /**
     * Convenience method to merge two XML nodes using default settings.
     */
    @Nullable
    public static XmlNode merge(XmlNode dominant, XmlNode recessive) {
        return merge(dominant, recessive, null);
    }

    /**
     * Merges two XML nodes.
     */
    @Nullable
    public static XmlNode merge(

            Properties merged = new Properties();
            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) {
                        mergePluginExecution(existing, element, sourceDominant, context);
                    } else {
                        merged.put(key, element.clone());
                    }
                }

                target.setExecutions(new ArrayList<>(merged.values()));
            }
        }

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

                target.setExecutions(new ArrayList<>(merged.values()));
            }
        }
    }

                merged.put(key, element);
            }

            for (Repository element : recessive) {
                Object key = getRepositoryKey(element);
                if (!merged.containsKey(key)) {
                    merged.put(key, element);
                }
            }

            target.setRepositories(new ArrayList<>(merged.values()));
        }
    }

        Properties merged = new Properties();
        if (sourceDominant) {
            merged.putAll(target.getProperties());
            merged.putAll(source.getProperties());
        } else {
            merged.putAll(source.getProperties());
            merged.putAll(target.getProperties());
        }
        target.setProperties(merged);
        target.setLocation(

                    );

            UpgradeResult merged = result1.merge(result2);

            assertTrue(merged.success(), "Merged result should be successful");
            assertEquals(2, merged.processedPoms().size(), "Should merge processed POMs");
            assertEquals(2, merged.modifiedPoms().size(), "Should merge modified POMs");
            assertTrue(merged.processedPoms().contains(pom1), "Should contain overlapping POM");

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

        Model merged = mavenMerger.merge(target, source, true, null);
        assertEquals(
                "SOURCE",
                merged.getArtifactId(),
                "Expected merged artifactId to be SOURCE but was " + merged.getArtifactId());

        merged = mavenMerger.merge(target, source, false, null);
        assertEquals(
                "TARGET",

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