Reduce Docker image size

Dockerfile

@@ -14,26 +14,25 @@ RUN apt-get update \
     && echo "sdkman_auto_selfupdate=false" >> $SDKMAN_DIR/etc/config \
     && echo "sdkman_insecure_ssl=true" >> $SDKMAN_DIR/etc/config
 
-ENV JDK8=$SDKMAN_DIR/candidates/java/8.0.222.hs-adpt
-RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh && sdk install java 8.0.222.hs-adpt"
-
-ENV JDK12=$SDKMAN_DIR/candidates/java/12.0.2-open
-RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh && sdk install java 12.0.2-open"
-
-ENV JDK13=$SDKMAN_DIR/candidates/java/13.ea.33-open
-RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh && sdk install java 13.ea.33-open"
-
-ENV JDK14=$SDKMAN_DIR/candidates/java/14.ea.11-open
-RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh && sdk install java 14.ea.11-open"
-
-# Set default JDK
-ENV JAVA_HOME=$JDK12 PATH="$JDK12/bin:${PATH}"
-RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh && sdk default java 12.0.2-open"
+RUN bash -c ". $SDKMAN_DIR/bin/sdkman-init.sh \
+    && sdk install java 8.0.222.hs-adpt \
+    && sdk install java 12.0.2-open \
+    && sdk install java 13.ea.33-open \
+    && sdk install java 14.ea.11-open \
+    && sdk flush archives \
+    && sdk flush temp"
+
+ENV JDK8=$SDKMAN_DIR/candidates/java/8.0.222.hs-adpt \
+    JDK12=$SDKMAN_DIR/candidates/java/12.0.2-open \
+    JDK13=$SDKMAN_DIR/candidates/java/13.ea.33-open \
+    JDK14=$SDKMAN_DIR/candidates/java/14.ea.11-open \
+    JAVA_HOME=$JDK12 \
+    PATH="$JDK12/bin:${PATH}"
 
 # Warm up Gradle caches
 RUN cd /tmp \
-    && git clone --depth 1 https://github.com/junit-team/junit5.git
-RUN cd /tmp/junit5 \
+    && git clone --depth 1 https://github.com/junit-team/junit5.git \
+    && cd /tmp/junit5 \
     && ./gradlew build -x test \
     && cd .. \
     && rm -rf junit5