Error:Error converting bytecode to dex:
Cause: Dex cannot parse version 52 byte code.
This is caused by library dependencies that have been compiled using Java 8 or above.
If you are using the 'java' gradle plugin in a library submodule add
targetCompatibility = '1.7'
sourceCompatibility = '1.7'
to that submodule's build.gradle file.
build.gradleに追記を行ってもダメな模様。Android版は別ブランチでリリースする予定