Upgrade to Ubuntu 20.04, OpenJDK 11 and Gerrit v3.2.0-rc0

Gerrit v3.2.0 brings the official support for Java 11,
therefore a major upgrade of Java and the Ubuntu version
are fully justified.

Ubuntu 20.04 distribution is the latest LTS distribution available.

Upgrade the following components:
- Gerrit: v3.2.0-rc0
- OpenJDK: v11
- Ubuntu: v20.04

Change-Id: I595303294017e587540a46a96741f3aaee8b8b03
diff --git a/ubuntu/18/.dockerignore b/ubuntu/20/.dockerignore
similarity index 100%
rename from ubuntu/18/.dockerignore
rename to ubuntu/20/.dockerignore
diff --git a/ubuntu/18/Dockerfile b/ubuntu/20/Dockerfile
similarity index 90%
rename from ubuntu/18/Dockerfile
rename to ubuntu/20/Dockerfile
index 4f78e69..ac98666 100644
--- a/ubuntu/18/Dockerfile
+++ b/ubuntu/20/Dockerfile
@@ -1,4 +1,4 @@
-FROM ubuntu:18.04
+FROM ubuntu:20.04
 MAINTAINER Gerrit Code Review Community
 
 # Add Gerrit packages repository
@@ -15,8 +15,8 @@
 
 # Install OpenJDK and Gerrit in two subsequent transactions
 # (pre-trans Gerrit script needs to have access to the Java command)
-RUN apt-get -y install openjdk-8-jdk
-RUN apt-get -y install gerrit=3.1.4-1 && \
+RUN apt-get -y install openjdk-11-jdk
+RUN apt-get -y install gerrit=3.2.0.rc0-1 && \
     apt-mark hold gerrit && \
     /entrypoint.sh init && \
     rm -f /var/gerrit/etc/{ssh,secure}* && rm -Rf /var/gerrit/{static,index,logs,data,index,cache,git,db,tmp}/* && chown -R gerrit:gerrit /var/gerrit
diff --git a/ubuntu/18/Dockerfile-dev b/ubuntu/20/Dockerfile-dev
similarity index 96%
rename from ubuntu/18/Dockerfile-dev
rename to ubuntu/20/Dockerfile-dev
index a0a35ae..5b8e50a 100644
--- a/ubuntu/18/Dockerfile-dev
+++ b/ubuntu/20/Dockerfile-dev
@@ -1,4 +1,4 @@
-FROM ubuntu:18.04
+FROM ubuntu:20.04
 MAINTAINER Gerrit Code Review Community
 
 ARG GERRIT_WAR_URL="https://gerrit-ci.gerritforge.com/view/Gerrit/job/Gerrit-bazel-master/lastSuccessfulBuild/artifact/gerrit/bazel-bin/release.war"
@@ -7,7 +7,7 @@
 RUN apt-get update && apt-get -y install \
     openssh-client \
     sudo \
-    openjdk-8-jdk \
+    openjdk-11-jdk \
     git && \
     rm -rf /var/lib/apt/lists/*
 
diff --git a/ubuntu/18/entrypoint.sh b/ubuntu/20/entrypoint.sh
similarity index 100%
rename from ubuntu/18/entrypoint.sh
rename to ubuntu/20/entrypoint.sh