* Update Gradle in generated Java projects from 2.14.1 to 6.0.1
* Upgrade Java 11 native Gradle from 5.5 to 6.0.1
When Java 11 native client library was introduced it was introduced with an overridden version of the Gradle wrapper (5.5 instead of 2.14.1). From looking at that PR, there doesn't appear to be any specific reason for the versions to differ. This removes the only override of the Gradle wrapper so all the Java projects are up to date and shares the same version.
* Add support for the google-api-client
* When there's no return type, just return (no parsing the response)
* Update the deserialization to use a Jackson typeref.
* Delete the auth mustache files as we don't need them
* Stop generating unneeded auth files; get SBT/gradle working with the generated module
* Add builder-style methods to the google-api-client ApiClient for getting API instances
* Update the README to reflect the new client library option
* Generated overloaded methods to send query params as a Map<String, Object>
* Add files for Sample codes
* Add type in angle brackets to support Java 6
* Required query params must be added to the Map of params. Update sample code.
* Use explicit types instead of diamonds to support Java6 in one more place.
* Clean up javadoc warnings in generated code / remove pointless return statements
* Clean up extra newlines in generated code
