[JAVA-8355] Move article code to spring-testing-2 module

testing-modules/spring-testing-2/src/main/java/com/baeldung/testexecutionlisteners/AdditionService.java

@@ -0,0 +1,10 @@
+package com.baeldung.testexecutionlisteners;
+
+import org.springframework.stereotype.Service;
+
+@Service
+public class AdditionService {
+    public int add(int a, int b) {
+        return a + b;
+    }
+}