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>

src/test/java/ca/uhn/fhir/jpa/starter/ExampleServerR5IT.java

@@ -45,15 +45,15 @@ public class ExampleServerR5IT {
   private IGenericClient ourClient;
   private FhirContext ourCtx;
 
-	public static final String SUBSCRIPTION_TOPIC_TEST_URL = "http://example.com/topic/test";
+  public static final String SUBSCRIPTION_TOPIC_TEST_URL = "http://example.com/topic/test";
 
 
-	@LocalServerPort
+  @LocalServerPort
   private int port;
 
 
   @Test
-  public void testCreateAndRead() {
+  void testCreateAndRead() {
 
     String methodName = "testCreateResourceConditional";
 
@@ -66,7 +66,7 @@ public class ExampleServerR5IT {
   }
 
   @Test
-  public void testWebsocketSubscription() throws Exception {
+  void testWebsocketSubscription() throws Exception {
 	  String endpoint = "ws://localhost:" + port + "/websocket";
     /*
      * Create topic