### Question:
GlobalLibraryVersionRegistrar { Set<LibraryVersion> getRegisteredVersions() { synchronized (infos) { return Collections.unmodifiableSet(infos); } } GlobalLibraryVersionRegistrar(); void registerVersion(String sdkName, String version); static GlobalLibraryVersionRegistrar getInstance();  }### Answer:
@Test public void getRegisteredVersions_returnsEmptySet_whenNoVersionsAreRegistered() { GlobalLibraryVersionRegistrar globalLibraryVersionRegistrar = new GlobalLibraryVersionRegistrar(); assertThat(globalLibraryVersionRegistrar.getRegisteredVersions()).isEmpty(); }