It seems that there's some issue with using Java 7 in the Docker image.
FAILURE: Build failed with an exception.
* Where:
Build file '/workspace/app/build.gradle' line: 16
* What went wrong:
A problem occurred evaluating project ':app'.
> java.lang.UnsupportedClassVersionError: com/android/build/gradle/AppPlugin : U nsupported major.minor version 52.0
* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.
BUILD FAILED
It seems that there's some issue with using Java 7 in the Docker image.