They way you are currently doing it is not the intended one. The developer is supposed to provide the client ID. Client IDs are (semi) public, which means you can and should include them in your code. I wrote semi public because you are not supposed to post them on forums and such to prevent people from just blindly copying your ID and thus misusing it, but including it in source code of your site or program is completly fine.
If the intended use of your code/library is to be included in another developer’s library and not as a standalone project then the other developer should use his ID and not yours though.