Small change to turn on Buildkit builder for all docker images.
set -euxo pipefail
+#Enable use of buildkit for all builds. No extra support in the docker file is required.
+export DOCKER_BUILDKIT=1
+
+
docker build --target ubuntu1604-java8 -t gcr.io/bazel-public/ubuntu1604:java8 .
docker build --target ubuntu1804-java11 -t gcr.io/bazel-public/ubuntu1804:java11 .
docker build --target ubuntu1804-nojava -t gcr.io/bazel-public/ubuntu1804:nojava .
