For some of the Xperia™ devices, we provide Android™ Open Source Project (AOSP) device configurations on GitHub. This means that the software will be open for you as a developer to use and contribute to. This is a way for us to support the open Android community, and it is also a tool for us to facilitate and verify contributions to AOSP.
Contribute - Sonyxperiadev GitHub
If you are interested in making contributions, head over to the project you’re interested in on GitHub. Make yourself familiar with the code, and feel free to have a look at the issue list to see where you might be able to help out. If you fork and improve our code, we encourage you to also contribute your work back to our repositories on our Sonyxperiadev GitHub account. We will review and merge your code as soon as possible. All contributions are handled through the GitHub tool.