The Google Play Game Services Publishing Java Library allows developers to integrate the Publishing API for Google Play Game Services into their Java applications. Developers can add the library to their Maven or Gradle projects using the code provided, or they can download the necessary jars as a zip file.
Google has long fielded complaints of sign-in requirements associated with Google Play Games. The Google+ requirement and multiple sign-ins required for multiple games has been a hotbed of frustration. Google announced the end of both requirements as part of a Google Play Games API model change.