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

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

src/test/java/ca/uhn/fhir/jpa/starter/SocketImplementation.java

@@ -18,7 +18,7 @@ public class SocketImplementation {
 	private final String myCriteria;
 	protected String myError;
 	protected boolean myGotBound;
-	private final List<String> myMessages = new ArrayList<String>();
+	private final List<String> myMessages = new ArrayList<>();
 	protected int myPingCount;
 	protected String mySubsId;
 	private Session session;