[REQ] [JAVA] Update Gradle used in generated projects

Created by: tobymurray

Is your feature request related to a problem? Please describe.

The version of Gradle used in generated Java projects is ~3 years out of date, but more importantly Gradle has changed dramatically in that time. The syntax used has evolved and the features available have improved. Using the current version in the generated projects (Gradle 2) is extremely limiting when it comes to adding things by overriding the templates.

Describe the solution you'd like

Upgrade Gradle to the latest version feasible

Describe alternatives you've considered

• Work around the issues outside of the generated project (works but it sucks)
• Upgrade Gradle in templates and override the old version (works but doesn't help community)