ROLLBACK_OF: Stop serializing the Class<MessageType> within Google (for now)

PiperOrigin-RevId: 493011985

java/core/src/main/java/com/google/protobuf/GeneratedMessageLite.java

@@ -1430,6 +1430,7 @@ public abstract class GeneratedMessageLite<
 
     // since v3.6.1
     private final Class<?> messageClass;
+    // only included for backwards compatibility before messageClass was added
     private final String messageClassName;
     private final byte[] asBytes;
 
@@ -1440,7 +1441,7 @@ public abstract class GeneratedMessageLite<
      */
     SerializedForm(MessageLite regularForm) {
       messageClass = regularForm.getClass();
-      messageClassName = regularForm.getClass().getName();
+      messageClassName = messageClass.getName();
       asBytes = regularForm.toByteArray();
     }