This resolves#5523
While bumping `com.android.tools.build:gradle:3.1.2` to `3.3.0`, some other plugins/artifacts/maven repo/buildscripts have to be updated:
- gradle (wrapper) need to upgrade to 4.10.x
- protobuf gradle plugin need to bump a version compatible with gradle version.
- need add `google()` and `jcenter()` repos for android (otherwise `com.android.tools.build:aapt2:3.3.0x` and `trove4j` will not be found resp.)
- need to accept license for Android "build-tools;28.0.3" in kokoro env.
The version bump happened in some places already, but many references
were missed.
This fixes the following warning that shows up with newer versions of
Gradle:
> Using TaskInputs.file() with something that doesn't resolve to a File
> object has been deprecated and is scheduled to be removed in Gradle
> 5.0. Use TaskInputs.files() instead.
Updates include:
* Build file and dependency updates
* Correcting the gradle wrapper for the clientcache example
* Lint fixes (including making AsyncTask subclasses static)
* Dropping the m-prefix from member variables
* Fixing the code indentation
* Fixing and enabling proguard for the routeguide example.
ZHANG Dapeng
Eric Anderson
Eric Gribkoff