Add a new integration test to validate that the built jars are compatible with Java 8.

[artursouza]

Describe the proposal

Create a new project (pom) that is written in Java 8 and consumes the build artifact from the SDK (like sdk-tests does) and show that the .jar is compatible with Java 8 applications.

[johnou]

How about using the animal sniffer plugin instead?

[beiwei30]

I like @johnou's idea to use animal sniffer to guard API compatibility, and made a quick change just now. @artursouza @johnou pls. review it.