#361 - Polishing.

Move EmbeddedMongo to utils module. Inline MongosSystemForTestFactory to control process output. Add Javadoc.

mongodb/transactions/src/main/java/example/springdata/mongodb/reactive/ReactiveTransitionService.java

@@ -53,7 +53,7 @@ public class ReactiveTransitionService {
 
 			return lookup(id) //
 					.flatMap(process -> start(action, process)) //
-					.flatMap(this::verify) //
+					.flatMap(it -> verify(it)) //
 					.flatMap(process -> finish(action, process));
 
 		}).next().map(Process::getId);