apache/dubbo

[Bug] dubbo-maven-pluggin cannot successfully compile google.protobuf.Empty into 'void' keyword

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#15629 opened on Aug 8, 2025

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 (1 comment) (0 reactions) (1 assignee)Java (41,524 stars) (26,453 forks)batch import
help wantedtype/bug

Description

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Apache Dubbo Component

Java SDK (apache/dubbo)

Dubbo Version

dubbo Version:3.3.5 dubbo-maven-pluggin version:3.3.5

Steps to reproduce this issue

issue discription : i use protobuf development style of triple protocal of dubbo 3.3.5 ,i build a new maven project to manage proto file and compiled java source code, finnally commit it to my local maven repsitory so that i can make full use of the compiled code.but when i define rpc service 'rpc xx (XXModel) returns (google.protobuf.Empty)' ,and then dubbo-maven-pluggin compile,after serval times checked it gengeate 'public xx(XXModel)' left void 'keyWord'

so it possible caused by dubbo-maven-pluggin

What you expected to happen

the void keyword appear successfully!!!

Anything else

No response

Are you willing to submit a pull request to fix on your own?

  • Yes I am willing to submit a pull request on my own!

Code of Conduct

Contributor guide

Tech stack
java
Domain
backendbuild system
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
4
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
mostly clear
Prerequisites
Knowledge of Apache DubboFamiliarity with Maven plugin developmentUnderstanding of protobuf code generation
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
25
Research direction
Start by examining the dubbo maven plugin module's code that processes protobuf definitions and generates Java stubs. Look for how it handles 'returns' clauses, particularly for well known types like google.protobuf.Empty. Check if there is a mapping from protobuf type to Java type that fails to recognize Empty as void. Also review any existing test cases for protobuf compilation to understand expected behavior. Finally, check the plugin's configuration options that might affect type mapping.