### Question:
RpcContext { @Override public String toString() { return "RpcContext{" + "applicationId='" + applicationId + '\'' + ", transactionServiceGroup='" + transactionServiceGroup + '\'' + ", clientId='" + clientId + '\'' + ", channel=" + channel + ", resourceSets=" + resourceSets + '}'; }  void release(); void holdInClientChannels(ConcurrentMap<Integer, RpcContext> clientTMHolderMap); void holdInIdentifiedChannels(ConcurrentMap<Channel, RpcContext> clientIDHolderMap); void holdInResourceManagerChannels(String resourceId, ConcurrentMap<Integer, RpcContext> portMap); void holdInResourceManagerChannels(String resourceId, Integer clientPort); ConcurrentMap<String, ConcurrentMap<Integer, RpcContext>> getClientRMHolderMap(); Map<Integer, RpcContext> getPortMap(String resourceId); String getClientId(); Channel getChannel(); void setChannel(Channel channel); String getApplicationId(); void setApplicationId(String applicationId); String getTransactionServiceGroup(); void setTransactionServiceGroup(String transactionServiceGroup); NettyPoolKey.TransactionRole getClientRole(); void setClientRole(NettyPoolKey.TransactionRole clientRole); String getVersion(); void setVersion(String version); Set<String> getResourceSets(); void setResourceSets(Set<String> resourceSets); void addResource(String resource); void addResources(Set<String> resources); void setClientId(String clientId); @Override String toString();  }### Answer:
@Test public void testToString() { rpcContext.setApplicationId(null); rpcContext.setTransactionServiceGroup(null); rpcContext.setClientId(null); rpcContext.setChannel(null); rpcContext.setResourceSets(null); Assertions.assertEquals( "RpcContext{" + "applicationId='" + rpcContext.getApplicationId() + '\'' + ", transactionServiceGroup='" + rpcContext.getTransactionServiceGroup() + '\'' + ", clientId='" + rpcContext.getClientId() + '\'' + ", channel=" + rpcContext.getChannel() + ", resourceSets=" + rpcContext.getResourceSets() + '}', rpcContext.toString()); }