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/MultitenantServerR4IT.java

@@ -26,7 +26,7 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
     "hapi.fhir.partitioning.partitioning_include_in_search_hashes=false",
 
   })
-public class MultitenantServerR4IT {
+class MultitenantServerR4IT {
 
 
   private static final org.slf4j.Logger ourLog = org.slf4j.LoggerFactory.getLogger(ExampleServerDstu2IT.class);
@@ -40,7 +40,7 @@ public class MultitenantServerR4IT {
 
 
   @Test
-  public void testCreateAndReadInTenantA() {
+  void testCreateAndReadInTenantA() {
 
 
     // Create tenant A
@@ -66,7 +66,7 @@ public class MultitenantServerR4IT {
   }
 
   @Test
-  public void testCreateAndReadInTenantB() {
+  void testCreateAndReadInTenantB() {
 
 
     // Create tenant A