Boyscouting (#558)

* Boyscouting: Docker conventions

* Boyscouting: JUnit 5 conventions ("It is generally recommended to omit the public modifier for test classes, test methods, and lifecycle methods unless there is a technical reason for doing so)"

* Boyscouting: typo in RepositoryValidationInterceptorFactoryDstu3

* Boyscouting: use List.of instead of Guava; use StandardCharsets instead of Guava; remove unused imports

---------

Co-authored-by: Gerlach, Winfried <Winfried.Gerlach@draeger.com>

Dockerfile

@@ -1,4 +1,4 @@
-FROM docker.io/library/maven:3.9.2-eclipse-temurin-17 as build-hapi
+FROM docker.io/library/maven:3.9.2-eclipse-temurin-17 AS build-hapi
 WORKDIR /tmp/hapi-fhir-jpaserver-starter
 
 ARG OPENTELEMETRY_JAVA_AGENT_VERSION=1.26.0
@@ -18,7 +18,7 @@ RUN mkdir /app && cp /tmp/hapi-fhir-jpaserver-starter/target/ROOT.war /app/main.
 
 ########### bitnami tomcat version is suitable for debugging and comes with a shell
 ########### it can be built using eg. `docker build --target tomcat .`
-FROM bitnami/tomcat:9.0 as tomcat
+FROM bitnami/tomcat:9.0 AS tomcat
 
 RUN rm -rf /opt/bitnami/tomcat/webapps/ROOT && \
     mkdir -p /opt/bitnami/hapi/data/hapi/lucenefiles && \
@@ -36,7 +36,7 @@ COPY --from=build-hapi --chown=1001:1001 /tmp/hapi-fhir-jpaserver-starter/opente
 ENV ALLOW_EMPTY_PASSWORD=yes
 
 ########### distroless brings focus on security and runs on plain spring boot - this is the default image
-FROM gcr.io/distroless/java17-debian11:nonroot as default
+FROM gcr.io/distroless/java17-debian11:nonroot AS default
 # 65532 is the nonroot user's uid
 # used here instead of the name to allow Kubernetes to easily detect that the container
 # is running as a non-root (uid != 0) user.