Use builder image that already has Gradle installed. I think I'm gett…

…ing the hang of this Docker thing.

Dockerfile

@@ -1,20 +1,11 @@
-FROM fabric8/java-centos-openjdk11-jdk as builder
-
-ARG CUSTOM_CRT_URL
+FROM gradle:6.5.1-jdk8 as builder
 
 USER root
 WORKDIR /
 
-# Build project and install connector
-RUN yum install -y git wget \
-   && git clone https://github.com/JeffersonLab/epics2kafka \
+RUN git clone https://github.com/JeffersonLab/epics2kafka \
    && cd epics2kafka \
-   && chmod +x gradlew \
-   && if [ -z "$CUSTOM_CRT_URL" ] ; then echo "No custom cert needed"; else \
-      wget --output-document=customcert.crt $CUSTOM_CRT_URL \
-      && echo "yes" | $JAVA_HOME/bin/keytool -import -trustcacerts -file customcert.crt -alias custom-ca -keystore $JAVA_HOME/lib/security/cacerts -storepass changeit \
-      ; fi \
-   && ./gradlew build -x test \
+   && gradle build -x test \
    && chmod +x ./scripts/*.sh
 
 FROM debezium/connect-base:1.3