private String contentCharset = DefaultManifest.DEFAULT_CONTENT_CHARSET;

    @Override
    public String getContentCharset() {
        return this.contentCharset;
    }

    @Override
    public void setContentCharset(String contentCharset) {
        if (contentCharset == null) {
            throw new InvalidUserDataException("contentCharset must not be null");
        }

        if (contentCharset == null) {
            throw new InvalidUserDataException("contentCharset must not be null");
        }
        if (!Charset.isSupported(contentCharset)) {
            throw new InvalidUserDataException(String.format("Charset for contentCharset '%s' is not supported by your JVM", contentCharset));
        }
        this.contentCharset = contentCharset;
    }

        new Manifest(IOUtils.toInputStream(content('META-INF/MANIFEST.MF'), contentCharset as String))
    }

    /**
     * Asserts that the Jar file is well-formed.
     */
    JarTestFixture(File file, String metadataCharset = 'UTF-8', String contentCharset = null) {
        this(file, metadataCharset, contentCharset, true)
    }

    /**
     * Creates the fixture.
     */

    private final Manifest delegate;
    private String contentCharset = DefaultManifest.DEFAULT_CONTENT_CHARSET;

    public CustomManifestInternalWrapper(Manifest delegate) {
        this.delegate = delegate;
    }

    @Override
    public String getContentCharset() {
        return contentCharset;
    }

    @Override
    public void setContentCharset(String contentCharset) {
        this.contentCharset = contentCharset;
    }

    protected final String contentCharset
    private final ListMultimap<String, Integer> compressionMethodsByRelativePath = ArrayListMultimap.create()

    ZipTestFixture(File file, String metadataCharset = null, String contentCharset = null) {
        new TestFile(file).assertIsFile()
        this.metadataCharset = metadataCharset ?: Charset.defaultCharset().name()
        this.contentCharset = contentCharset ?: Charset.defaultCharset().name()

    }

    private static String getContentForEntry(TarArchiveEntry entry, TarArchiveInputStream inputStream, String contentCharset) {
        byte[] content = IOUtils.readFully(inputStream, (int) entry.getSize())
        new String(content, contentCharset ?: Charset.defaultCharset().name())
    }

    /**
     * The character set used to decode the merged manifest content.
     *
     * @param contentCharset the character set used to decode the merged manifest content
     * @see #getContentCharset()
     * @since 2.14
     */
    void setContentCharset(String contentCharset);

    /**
     * Adds a merge path to a manifest that should be merged into the base manifest. A merge path can be either another

        "'UTF-8'"       | "'UNSUPPORTED'" | "Charset for contentCharset 'UNSUPPORTED' is not supported by your JVM"
        null            | "'UTF-8'"       | "manifestContentCharset must not be null"
        "'UTF-8'"       | null            | "contentCharset must not be null"
    }

    private static String customJarManifestTask() {
        return '''

     */
    String getContentCharset();

    /**
     * See {@link org.gradle.jvm.tasks.Jar#getManifestContentCharset()}
     */
    void setContentCharset(String contentCharset);

    /**
     * Writes the manifest into a stream.
     *
     * The manifest will be encoded using the character set defined by the {@link #getContentCharset()} property.
     *