public static String getManifestKey(File aJarFile, String key) {
        try (JarFile jarFile = new JarFile(aJarFile)) {
            return getManifestKey(jarFile, key);
        } catch (IOException e) {
            LOG.error("Exception while trying to read key {} from manifest of {}", key, aJarFile, e);
        }
        return null;
    }
@Test
    public void shouldGetManifestKey() throws Exception {
        String manifestKey = JarUtil.getManifestKey(new File(PATH_WITH_HASHES + "test-agent.jar"), "Go-Agent-Bootstrap-Class");
        assertThat(manifestKey, is("com.thoughtworks.go.HelloWorldStreamWriter"));
    }