bom: Remove protoc-gen-grpc-java

[ejona86]

protoc-gen-grpc-java isn't useful in a BOM because the Gradle plugin
doesn't support BOMs (google/protobuf-gradle-plugin#412) and it seems
unlikely the Maven plugin would as well.

Right now the type is pom, which is useless; nobody cares about the pom
itself. We'd need to use a type of exe and repeat it for each platform
(classifier). Given that it is a strange case and we can't actually test
the results and having it in the bom might lead a user to trying to make
it work, let's just remove it for now until it provides value.

Fixes #8936

[danielnorberg]

👍

This would break the build for maven projects that have a (useless) dependency on protoc-gen-grpc-java and relies on it being managed:

<dependencyManagement>
  <dependencies>
    <dependency>
      <groupId>io.grpc</groupId>
      <artifactId>grpc-bom</artifactId>
      <version>1.45.0</version>
      <scope>import</scope>
      <type>pom</type>
    </dependency>
  </dependencies>
</dependencyManagement>

<dependencies>
  <dependency>
    <groupId>io.grpc</groupId>
    <artifactId>protoc-gen-grpc-java</artifactId>
    <type>pom</type>
  </dependency>
</dependencies>

They would then get the following error if we remove protoc-gen-grpc-java from grpc-bom:

[ERROR]     'dependencies.dependency.version' for io.grpc:protoc-gen-grpc-java:pom is missing. @ line X, column Y

Hopefully this is rare in the wild. I did not find any such users in our internal index.

[ejona86]

Yeah, that should be rare and should only break on a version upgrade, at which point the solution is "delete the useless dependency that does nothing." So I'm not very concerned.

[ST-DDT]

FFR: I used the version from the bom in my gradle project and v1.46.0 broke the ci build.
I will add it there now to fix the issue:

• https://github.com/yidongnan/grpc-spring-boot-starter/blob/2d2b9af8424c65cc76cc075d6217319d393a8ecb/tests/build.gradle#L44
• https://github.com/yidongnan/grpc-spring-boot-starter/blob/2d2b9af8424c65cc76cc075d6217319d393a8ecb/examples/grpc-lib/build.gradle#L26

IMO its a bug in the maven plugin that it doesn't use the version from the bom.

[ejona86]

@ST-DDT, I mention I didn't think it worked for gradle as well and linked to an issue. Looks like you are using dependencyManagement in buildscript. Interesting. We'll revert this.