Java class generated from protobuf has compilation errors - protocol-buffers

Question

I'm trying to generated java classes from protobuf.
Below is my protobuf -
syntax = "proto2";
package part2;
option java_package = "part2";
message OnlineStoreUser {
required int32 userid = 1;
required string username = 2;
optional string useremail = 3;
}
I run the command main/exec/protoc --java_out=main/java main/proto/datamodel.proto
The protoc is downloaded from
link https://github.com/protocolbuffers/protobuf/releases/tag/v3.7.1 where osx-x86_64.zip. I tried version 3.8.0 and 3.9.1 as well.
First error is https://gist.github.com/rajcspsg/07c1ddb889410397ba6fc6f26ab2b158#file-gistfile1-txt-L78. The argument to this function UnusedPrivateParameter type is not found.
Second error is https://gist.github.com/rajcspsg/07c1ddb889410397ba6fc6f26ab2b158#file-gistfile1-txt-L890. The is no 2 arg overloaded version of internalBuildGeneratedFileFrom.
What is wrong with my proto file. How can I fix this issue?

Answer 1

Make sure the dependency that you're using in your code is the same as the one that you used as protobuf compiler, for example, here I'm using gradle:
compile group: 'com.google.protobuf', name: 'protobuf-java', version: '3.11.1'
And the for my compiler version is:
✗ protoc --version
libprotoc 3.11.1
Here's my test event:
syntax = "proto2";
option java_package = "com.github.irvifa.protobuf.schema";
message TestEvent {
optional string event_name = 1 [default = "test.event"];
optional string name = 2;
optional string email = 3;
}
And this works.

Answer 2

The errors you mention only happen for me with version 3.9.1. Version 3.7.1 generates a file that doesn't use the UnusedPrivateParameter or the version of internalBuildGeneratedFileFrom with 2 parameters. It rather uses the version with 3 parameters, which does not cause any errors.
Please check that you are using the correct protoc version:
$ main/exec/protoc --version
libprotoc 3.7.1