Older version Gmail API jar might not work well with the recent version of Gmail services. I am not sure, but the google-api-client-1.23.0 has already been updated to 1.31.3 until now. I suppose there have been many changes in the Gmail service. Therefore I guess @plaidshirtakos may find that he really need the recent version of google-api-client-x.x.x.jar such as 1.31.3. In this case he will get stuck, as he can not take the initiative to choose the versions of Google API.
The Gmail API used by the “Read and Write Gmail Messages plugin” might be too old to work with the recent version of Gmail service. This might be the reason why many people report problems about the plugin. For example,