examples: make JSON code more obviously advanced

examples/src/main/java/io/grpc/examples/helloworld/HelloJsonClient.java

@@ -46,6 +46,15 @@ import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
+/**
+ * Advanced example of how to swap out the serialization logic.  Normal users do not need to do
+ * this.  This code is not intended to be a production-ready implementation, since JSON encoding
+ * is slow.  Additionally, JSON serialization as implemented may be not resilient to malicious
+ * input.
+ *
+ * <p>If you are considering implementing your own serialization logic, contact the grpc team at
+ * https://groups.google.com/forum/#!forum/grpc-io
+ */
 public final class HelloJsonClient {
   private static final Logger logger = Logger.getLogger(HelloWorldClient.class.getName());
 

examples/src/main/java/io/grpc/examples/helloworld/HelloJsonServer.java

@@ -45,6 +45,14 @@ import java.util.logging.Logger;
 
 /**
  * Server that manages startup/shutdown of a {@code Greeter} server.
+ *
+ * <p>This is an advanced example of how to swap out the serialization logic.  Normal users do not
+ * need to do this.  This code is not intended to be a production-ready implementation, since JSON
+ * encoding is slow.  Additionally, JSON serialization as implemented may be not resilient to
+ * malicious input.
+ *
+ * <p>If you are considering implementing your own serialization logic, contact the grpc team at
+ * https://groups.google.com/forum/#!forum/grpc-io
  */
 public class HelloJsonServer {
   private static final Logger logger = Logger.getLogger(HelloWorldServer.class.getName());