### Question:
DecompressorRegistry { @ExperimentalApi("https: public Set<String> getAdvertisedMessageEncodings() { Set<String> advertisedDecompressors = new HashSet<String>(decompressors.size()); for (Entry<String, DecompressorInfo> entry : decompressors.entrySet()) { if (entry.getValue().advertised) { advertisedDecompressors.add(entry.getKey()); } } return Collections.unmodifiableSet(advertisedDecompressors); } private  DecompressorRegistry(Decompressor d, boolean advertised, DecompressorRegistry parent); private  DecompressorRegistry(); static DecompressorRegistry emptyInstance(); static DecompressorRegistry getDefaultInstance(); DecompressorRegistry with(Decompressor d, boolean advertised); Set<String> getKnownMessageEncodings(); @ExperimentalApi("https://github.com/grpc/grpc-java/issues/1704") Set<String> getAdvertisedMessageEncodings(); @Nullable Decompressor lookupDecompressor(String messageEncoding);  }### Answer:
@Test public void getAdvertisedMessageEncodings_noEncodingsAdvertised() { assertTrue(registry.getAdvertisedMessageEncodings().isEmpty()); }