[P2] Proposal: IDL Generator From Java Source Code

[felix021]

The goal of this proposal is to implement a tool which generates a Thrift IDL by parsing Java source code from an existing Dubbo Java project.

The generated Thrift IDL should contain necessary tags, such as JavaInterfaceName on services and JavaClassName on structs, so that it can be used to generate Kitex client/server scaffold.

[DMwangnima]

BTW, we need to implement generating a Dubbo Java interface file from the thrift IDL. This is very useful in Dubbo Java client -> Kitex server.