* 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.
* WIP: CodegenProperty with XML
* WIP: CodegenModel XML bits
* WIP: Jackson XML
* WIP: Java templating
* WIP: Java client withXml flag
* WIP: resttemplate work
* WIP: withXml only when Jackson is used
* WIP: Tabs to spaces
* WIP: java-petstore-resttemplate-withxml sample
* WIP: language: spring
* WIP: language "spring" using library "spring-boot" should include apiPackage in @ComponentScan to detect the API
* WIP: javax.xml for non-Jackson Java and enabled payload logging for jersey2
* WIP: updated java petstore samples
* WIP: JavaSpring with non-jackson XML
* WIP: bin/spring-all-pestore.sh