* Upgrade Gradle plugin Gradle build to Gradle 7.5.1

* Update Travis workflow file to support new tasks

* Update Maven POM with Gradle 7.5.1

* Capitalize many occurrences of "Gradle" in the Gradle plugin README

* Update Gradle version in appveyor.yml and shippable.yml

* Update comments

* Update Gradle wrapper to 7.5.1

* Capitalize Gradle in shippable.yml

* Leave Open API

* Upgrade Gradle plugin build to Gradle 7.6

* Upgrade wrapper to Gradle 7.6