### Question:
JwtBundleSet implements BundleSource<JwtBundle> { public static JwtBundleSet emptySet() { return new JwtBundleSet(); } private  JwtBundleSet(final Map<TrustDomain, JwtBundle> bundles); private  JwtBundleSet(); static JwtBundleSet of(@NonNull final Collection<JwtBundle> bundles); static JwtBundleSet emptySet(); @Override JwtBundle getBundleForTrustDomain(@NonNull final TrustDomain trustDomain); Map<TrustDomain, JwtBundle> getBundles(); void put(@NonNull final JwtBundle jwtBundle);  }### Answer:
@Test void testEmptySet() { JwtBundleSet jwtBundleSet = JwtBundleSet.emptySet(); assertNotNull(jwtBundleSet); assertEquals(0, jwtBundleSet.getBundles().size()); }