### Question:
BridgeSerializationUtils { public static byte[] serializeReleaseTransactionSet(ReleaseTransactionSet set) { List<ReleaseTransactionSet.Entry> entries = set.getEntries().stream().collect(Collectors.toList()); entries.sort(ReleaseTransactionSet.Entry.ULD_TX_COMPARATOR); byte[][] bytes = new byte[entries.size() * 2][]; int n = 0; for (ReleaseTransactionSet.Entry entry : entries) { bytes[n++] = RLP.encodeElement(entry.getTransaction().ulordSerialize()); bytes[n++] = RLP.encodeBigInteger(BigInteger.valueOf(entry.getUscBlockNumber())); } return RLP.encodeList(bytes); } private  BridgeSerializationUtils(); static byte[] serializeMap(SortedMap<Keccak256, UldTransaction> map); static SortedMap<Keccak256, UldTransaction> deserializeMap(byte[] data, NetworkParameters networkParameters, boolean noInputsTxs); static byte[] serializeUTXOList(List<UTXO> list); static List<UTXO> deserializeUTXOList(byte[] data); static byte[] serializeSet(SortedSet<Sha256Hash> set); static SortedSet<Sha256Hash> deserializeSet(byte[] data); static byte[] serializeMapOfHashesToLong(Map<Sha256Hash, Long> map); static Map<Sha256Hash, Long> deserializeMapOfHashesToLong(byte[] data); static byte[] serializeFederation(Federation federation); static Federation deserializeFederation(byte[] data, Context uldContext); static byte[] serializePendingFederation(PendingFederation pendingFederation); static PendingFederation deserializePendingFederation(byte[] data); static byte[] serializeElection(ABICallElection election); static ABICallElection deserializeElection(byte[] data, AddressBasedAuthorizer authorizer); static byte[] serializeOneOffLockWhitelist(Pair<List<OneOffWhiteListEntry>, Integer> data); static byte[] serializeUnlimitedLockWhitelist(List<UnlimitedWhiteListEntry> entries); static Pair<HashMap<Address, OneOffWhiteListEntry>, Integer> deserializeOneOffLockWhitelistAndDisableBlockHeight(byte[] data, NetworkParameters parameters); static Map<Address, UnlimitedWhiteListEntry> deserializeUnlimitedLockWhitelistEntries(byte[] data, NetworkParameters parameters); static byte[] serializeCoin(Coin coin); @Nullable static Coin deserializeCoin(byte[] data); static byte[] serializeReleaseRequestQueue(ReleaseRequestQueue queue); static ReleaseRequestQueue deserializeReleaseRequestQueue(byte[] data, NetworkParameters networkParameters); static byte[] serializeReleaseTransactionSet(ReleaseTransactionSet set); static ReleaseTransactionSet deserializeReleaseTransactionSet(byte[] data, NetworkParameters networkParameters);  }### Answer:
@Test public void serializeTransactionSet() throws Exception { PowerMockito.mockStatic(RLP.class); mock_RLP_encodeElement(); mock_RLP_encodeBigInteger(); mock_RLP_encodeList(); Set<ReleaseTransactionSet.Entry> sampleEntries = new HashSet<>(Arrays.asList( new ReleaseTransactionSet.Entry(mockUldTransactionSerialize("ccdd"), 10L), new ReleaseTransactionSet.Entry(mockUldTransactionSerialize("bb"), 20L), new ReleaseTransactionSet.Entry(mockUldTransactionSerialize("ba"), 30L), new ReleaseTransactionSet.Entry(mockUldTransactionSerialize("aa"), 40L) )); ReleaseTransactionSet sample = new ReleaseTransactionSet(sampleEntries); byte[] result = BridgeSerializationUtils.serializeReleaseTransactionSet(sample); String hexResult = Hex.toHexString(result); StringBuilder expectedBuilder = new StringBuilder(); expectedBuilder.append("ddaa"); expectedBuilder.append("ff28"); expectedBuilder.append("ddba"); expectedBuilder.append("ff1e"); expectedBuilder.append("ddbb"); expectedBuilder.append("ff14"); expectedBuilder.append("ddccdd"); expectedBuilder.append("ff0a"); assertEquals(expectedBuilder.toString(), hexResult); }