### Question:
ManifestExtractor { public Map<String, String> extractFromManifest(String manifestImplementationName) { Optional<Manifest> manifest = getManifest(manifestImplementationName); return manifest.map(this::filterManifestValues) .orElseGet(Collections::emptyMap); }  Map<String, String> extractFromManifest(String manifestImplementationName);  }### Answer:
@Test public void testUnknownManifest() { Map<String, String> stringStringMap = new ManifestExtractor().extractFromManifest("non-existing-manifest"); assertThat(stringStringMap.size(), is(0)); }
@Test public void testKnownManifest() { Map<String, String> stringStringMap = new ManifestExtractor().extractFromManifest("JUnit"); assertThat(stringStringMap.size(), is(3)); assertThat(stringStringMap.get("Implementation-Title"), is("JUnit")); assertThat(stringStringMap.get("Implementation-Version"), containsString("4.")); assertThat(stringStringMap.get("Implementation-Vendor-Id"), is("junit")); }