message: [java] Pin to Gradle 6
  The Java Gradle files use Gradle 6 features, like `maven`. Newer
  versions of Gradle do not support this.
  Pin to Gradle 6 until this can be reworked.
diff: @@ -52,7 +52,7 @@ RUN nuget install NUnit.ConsoleRunner -OutputDirectory /root -Version 3.8.0 -Non
  RUN add-apt-repository ppa:cwchien/gradle && \
  apt-get update && \
  apt-get -y install \
  - gradle \
  + gradle-6.8.3 \
  openjdk-8-jdk-headless
  # Components for ghc
  