Asking for a list of commits from a PR that has been a sourced from a search results in GHFileNotFoundException

[NlightNFotis]

Describe the bug

Hello.

I'm writing a test program to evaluate the library:

package org.example;

import org.kohsuke.github.*;

public class Main {

    public static void main(String[] args) {
        System.out.println("Hello world from Github API Experiment!");
        String token = "xxx";

        try {
            // Connect
            GitHub github = new GitHubBuilder().withOAuthToken(token).build();
            System.out.println("Built Github API bridge");
            System.out.println("With valid credential: " + github.isCredentialValid());

            // Get ref from environment
            String ref_name = System.getenv("GITHUB_REF_NAME");
            System.out.println("Ref name is " + ref_name);

            GHRepository repo = github.getRepository("NlightNFotis/demo-spring-petclinic");

            // Create branch out of ref
            GHBranch pr_branch = repo.getBranch(ref_name);

            // Find pull request corresponding to ref
            GHPullRequestSearchBuilder builder = repo.searchPullRequests().isOpen();
            var pr_list = builder.list();
            System.out.println("PRs found " + pr_list.getTotalCount());

            // Iterate through PRs
            for (var pr : pr_list) {
                System.out.println("PR URL: " + pr.listCommits().toArray()[0].getUrl());
            }
        } catch (Exception e) {
            System.out.println("Got an exception: " + e.getMessage());
        }
    }
}

This unfortunately results in a 404 from Github's endpoint, with the output being the following:

Hello world from Github API Experiment!
Built Github API bridge
With valid credential: true
Ref name is cover_action
PRs found 1
Got an exception: https://api.github.com/repos/NlightNFotis/demo-spring-petclinic/issues/1/commits {"message":"Not Found","documentation_url":"https://docs.github.com/rest"}

The error that shows up is a GHFileNotFoundException.

I spent some time trying to debug it, and I understand that the issue is because of the /issues/ path in the URL being queried. If I change the URL to point to /pulls/ instead of /issues/ in a debugger, the issue vanishes: https://api.github.com/repos/NlightNFotis/demo-spring-petclinic/pulls/1/commits.

I have managed to identify the culprit as the GHPullRequest.getApiRoute method.

/**
     * Gets the api route.
     *
     * @return the api route
     */
    @Override
    protected String getApiRoute() {
        if (owner == null) {
            // Issues returned from search to do not have an owner. Attempt to use url.
            final URL url = Objects.requireNonNull(getUrl(), "Missing instance URL!");
            return StringUtils.prependIfMissing(url.toString().replace(root().getApiUrl(), ""), "/");
        }
        return "/repos/" + owner.getOwnerName() + "/" + owner.getName() + "/pulls/" + number;
    }

What I understand about the issue is:

1. In my code, I retrieve pull requests using a search. This results in objects that have no owner.
2. Inside of GHPullRequest.getApiRoute, the owner == null path is being followed, trying to compensate for the lack of an owner by trying to get an API URL from previous API responses.
3. This results in a URL that contains the /issues/ path, e.g. repos/NlightNFotis/demo-sping-petclinic/issues/, which is then appended to by other queries, such as listCommits().
4. The request is then sent to GitHub, resulting in a 404.

Expected behavior

If I build with a patched version locally, I get the (expected) output of:

Hello world from Github API Experiment!
Built Github API bridge
With valid credential: true
Ref name is cover_action
PRs found 1
PR URL: https://github.com/NlightNFotis/demo-spring-petclinic/commit/c0b514d30b11a03dbaea71cebec4d4f6cad0f45a

Desktop (please complete the following information):

• OS: [e.g. iOS] MacOS Sonoma 14.0
• Browser [e.g. chrome, safari] Safari 17.0
• Version [e.g. 22] 1.319

Additional context

I have a fix and a regression test locally that I will try to push. It's a drive by change, so I don't know if it satisfies the quality standards of the project, though I have taken every care to try to meet them.