Align CI image to expose javadoc binary

ci/images/initializr-ci-image/Dockerfile

@@ -1,11 +1,7 @@
 FROM ubuntu:bionic-20181018
 
-ENV JAVA_HOME /opt/openjdk
-ENV PATH $JAVA_HOME/bin:$PATH
-RUN apt-get update && \
-	apt-get install --no-install-recommends -y ca-certificates net-tools libxml2-utils git curl libudev1 libxml2-utils iptables iproute2 jq
-RUN mkdir -p /opt/openjdk && \
-    cd /opt/openjdk && \
-    curl https://java-buildpack.cloudfoundry.org/openjdk/bionic/x86_64/openjdk-1.8.0_192.tar.gz | tar xz
+ADD setup.sh /setup.sh
+RUN ./setup.sh
 
-ADD https://raw.githubusercontent.com/spring-io/concourse-java-scripts/v0.0.2/concourse-java.sh /opt/
+ENV JAVA_HOME /opt/openjdk
+ENV PATH $JAVA_HOME/bin:$PATH

ci/images/setup.sh

@@ -0,0 +1,24 @@
+#!/bin/bash
+set -ex
+
+###########################################################
+# UTILS
+###########################################################
+
+apt-get update
+apt-get install --no-install-recommends -y ca-certificates net-tools libxml2-utils git curl libudev1 libxml2-utils iptables iproute2 jq
+rm -rf /var/lib/apt/lists/*
+
+curl https://raw.githubusercontent.com/spring-io/concourse-java-scripts/v0.0.2/concourse-java.sh > /opt/concourse-java.sh
+
+
+###########################################################
+# JAVA
+###########################################################
+JDK_URL=https://github.com/AdoptOpenJDK/openjdk8-binaries/releases/download/jdk8u202-b08/OpenJDK8U-jdk_x64_linux_hotspot_8u202b08.tar.gz
+
+mkdir -p /opt/openjdk
+cd /opt/openjdk
+curl -L ${JDK_URL} | tar zx --strip-components=1
+test -f /opt/openjdk/bin/java
+test -f /opt/openjdk/bin/javac