### Question:
PersistenceUnitMetadata implements PersistenceUnitInfo { public void addJarFile(String jarFile) { if (jarFiles == null) { jarFiles = new HashSet<String>(); } this.jarFiles.add(jarFile); addJarFileUrl(jarFile); } PersistenceUnitMetadata();  PersistenceUnitMetadata(String xmlSchemaVersion, URL rootUrl, URL mappingFileUrl); @Override String getPersistenceUnitName(); void setPersistenceUnitName(String persistenceUnitName); void setTransactionType(PersistenceUnitTransactionType transactionType); void setProvider(String provider); List<String> getClasses(); void setClasses(List<String> classes); List<String> getPackages(); void setPackages(List<String> packages); Set<String> getJarFiles(); void addJarFile(String jarFile); boolean getExcludeUnlistedClasses(); void setExcludeUnlistedClasses(boolean excludeUnlistedClasses); @Override String toString(); @Override String getPersistenceProviderClassName(); @Override PersistenceUnitTransactionType getTransactionType(); @Override DataSource getJtaDataSource(); @Override DataSource getNonJtaDataSource(); @Override List<String> getMappingFileNames(); @Override List<URL> getJarFileUrls(); @Override URL getPersistenceUnitRootUrl(); @Override List<String> getManagedClassNames(); @Override boolean excludeUnlistedClasses(); @Override SharedCacheMode getSharedCacheMode(); @Override ValidationMode getValidationMode(); @Override Properties getProperties(); void setProperties(Properties properties); @Override String getPersistenceXMLSchemaVersion(); @Override ClassLoader getClassLoader(); @Override void addTransformer(ClassTransformer paramClassTransformer); @Override ClassLoader getNewTempClassLoader(); String getProperty(String prop); List<URL> getManagedURLs(); String getClient(); int getBatchSize(); URL getMappedUrl();  }### Answer:
@Test public void testAddJarFile() { Assert.assertNotNull(metadatas); Assert.assertFalse(metadatas.isEmpty()); Assert.assertNotNull(metadatas.get(0)); PersistenceUnitMetadata puMetadata = metadatas.get(0); puMetadata.addJarFile("myJarFile.jar"); Assert.assertNotNull(puMetadata.getJarFiles()); Assert.assertFalse(puMetadata.getJarFiles().isEmpty()); Assert.assertNotNull(puMetadata.getJarFileUrls()); Assert.assertFalse(puMetadata.getJarFileUrls().isEmpty()); }