Any differences between proto2 and proto3 generated code are highlighted—note that these differences are in the generated code as described in this document, not the base message classes/interfaces, which are the same in both versions. You should read the proto2 language guide and/or proto3 language guide before reading this document. Compiler Invocation The protocol buffer compiler produces Kotlin code that builds on top of Java code. As a result, it must be invoked with two command-line f...