Pin Docker image eclipse-temurin:17-jre-focal

eclipse-temurin:17-jre-focal
->
eclipse-temurin:17-jre-focal@sha256:55c1ff40a91898c456dc5a874a66db17b6aa1b4aef8d9cac1ad3b194575638a1

 [atomist:generated]
 [atomist-skill:atomist/docker-base-image-policy]

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sparkjava-mysql/backend/Dockerfile

@@ -24,7 +24,7 @@ EOF
 COPY --from=gloursdocker/docker / /
 CMD ["java", "-jar", "target/app.jar" ]
 
-FROM eclipse-temurin:17-jre-focal
+FROM eclipse-temurin:17-jre-focal@sha256:55c1ff40a91898c456dc5a874a66db17b6aa1b4aef8d9cac1ad3b194575638a1
 ARG DEPENDENCY=/workdir/server/target
 EXPOSE 8080
 COPY --from=build ${DEPENDENCY}/app.jar /app.jar