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/ExampleServerR4IT.java

@@ -87,7 +87,7 @@ class ExampleServerR4IT {
 	}
 
 	@Test
-	public void testBatchPutWithIdenticalTags() {
+	void testBatchPutWithIdenticalTags() {
 		String batchPuts = "{\n" +
 			"\t\"resourceType\": \"Bundle\",\n" +
 			"\t\"id\": \"patients\",\n" +