I have made a change to preserve the old addHook(..) method to avoid breaking changes.

I also think that org.gitlab4j.api.ProjectApi.addHook(Object, String, ProjectHook, Boolean, String) is the method that is maintained and that should be used. So your method is now delegating to this method.

I believe that the API change of the fourth argument boolean (primitive type, nulls not allowed) to Boolean (object, nulls allowed) is a breaking change. The change in the diff went from this:

    public ProjectHook addHook(Object projectIdOrPath, String url, ProjectHook enabledHooks,
            boolean enableSslVerification, String secretToken) throws GitLabApiException {

to this:

    public ProjectHook addHook(Object projectIdOrPath, String url, ProjectHook enabledHooks,
            Boolean enableSslVerification, String secretToken) throws GitLabApiException {

The Jenkins issue tracker received two reports of method not found exceptions in issue JENKINS-73672.

Is there a critical need for the change of type in the argument?

If not, could that change be reverted and a new release provided so that API compatibility is retained?