feature: Add context object pattern (#2304)

* Add context object pattern and corresponding tests

* Update context pattern

* Add README, class diagram, puml file.
Add toString method in ServiceContext.java.
Add tests for coverage.

* Improvements:
Remove plugin in pom file
Add comments in app.java
Change local variable keyword to var in app.java
Use lombok for getters, setters and tostring
Change method signature in context object

* Refreshing environment-1

* Reconfigure pom file.

Co-authored-by: Alvis Chan <u7287079@edu.anu.au>
Co-authored-by: u7287079 <u7287079@anu.edu.au>

context-object/src/main/java/com/iluwatar/context/object/LayerB.java

@@ -0,0 +1,17 @@
+package com.iluwatar.context.object;
+
+import lombok.Getter;
+
+@Getter
+public class LayerB {
+
+    private ServiceContext context;
+
+    public LayerB(LayerA layerA) {
+        this.context = layerA.getContext();
+    }
+
+    public void addSessionInfo(String sessionService) {
+        context.setSessionService(sessionService);
+    }
+}