dest.setBbb("bbb");
        dest.setDdd("ddd");

        BeanUtil.copyBeanToBean(src, dest);
        assertThat(dest.getAaa(), is("111"));
        assertThat(dest.getBbb(), is(nullValue()));
        assertThat(dest.getDdd(), is("ddd"));
    }

    /**
     * @throws Exception
     */
    @Test
    public void testCopy_BeanToBean_ExcludeNull() throws Exception {
        final MyClass src = new MyClass();

    @Mock
    private MessageDigest mockMd5;

    @BeforeEach
    void setUp() throws NoSuchAlgorithmException {
        // Mock Crypto.getMD5() to return our mockMd5 instance
        // This requires Mockito 3.4.0+ for MockedStatic
        // For simplicity, we'll assume Crypto.getMD5() is static and mock it.
        // If it's not static, we'd need to inject it or mock the class that provides it.

    public static byte[] getNTHash(final String password) {
        if (password == null) {
            throw new NullPointerException("Password parameter is required");
        }
        final MessageDigest md4 = Crypto.getMD4();
        md4.update(Strings.getUNIBytes(password));
        return md4.digest();
    }

    /**
     * Generates the NT password hash for the given password.

                if (!serverIds.add(server.getId())) {
                    addViolation(
                            problems,
                            Severity.WARNING,
                            "servers.server.id",
                            null,
                            "must be unique but found duplicate server with id " + server.getId());
                }
            }

                            }
                        }
                    }
                }

                // org.eclipse.aether.ConfigurationProperties.HTTP_HEADERS => Map<String, String>
                if (headers != null) {
                    configProps.put(ConfigurationProperties.HTTP_HEADERS + "." + server.getId(), headers);
                }

                repoIds.add(repository.getId());
                artifactRepositories.add(repository);
            }
        }

        if (recessiveRepositories != null) {
            for (ArtifactRepository repository : recessiveRepositories) {
                if (repoIds.add(repository.getId())) {
                    artifactRepositories.add(repository);
                }

                if (!repos.containsKey(repo.getId())) {
                    repos.put(repo.getId(), repo);
                }
            }

            for (ArtifactRepository repo : pomRepositories) {
                if (!repos.containsKey(repo.getId())) {
                    repos.put(repo.getId(), repo);
                }
            }

    @Override
    public MavenExecutionRequest addProxy(Proxy proxy) {
        Objects.requireNonNull(proxy, "proxy cannot be null");

        for (Proxy p : getProxies()) {
            if (p.getId() != null && p.getId().equals(proxy.getId())) {
                return this;
            }
        }

        getProxies().add(proxy);

        return this;
    }

    @Override

                + version;
    }

    private static String getId(Artifact artifact) {
        return getId(
                artifact.getGroupId(),
                artifact.getArtifactId(),
                artifact.getExtension(),
                artifact.getClassifier(),
                artifact.getBaseVersion());
    }

    private static String getId(ClassRealmConstituent constituent) {
        return getId(

            }
        }

        private void visit(Activation activation) {
            if (activation != null) {
                String org, val;
                // Jdk
                org = activation.getJdk();
                val = interpolate(org);
                if (org != val) {
                    activation.setJdk(val);
                }
                // OS
                visit(activation.getOs());