feat: Add Thread-Specific Storage design pattern (#3422)

* Add Thread-Specific Storage design pattern

* fixed:pom.xml
Run 'mvn spotless:apply' to fix these violations.

* fix: address Sonar security hotspots for Random usage and e.printStackTrace()

* fixed:
Run 'mvn spotless:apply'(remove unused import)

* fixed:
Refactor Thread-Specific Storage pattern implementation to address Sonar issues: remove unnecessary instantiation, add private constructor, use diamond operator, and update tests.

* fixed:
update uml and README.md

* Trigger CI rerun

thread-specific-storage/etc/thread-specific-storage.urm.puml

@@ -0,0 +1,41 @@
+@startuml
+package thread-specific-storage {
+
+  class APP {
+    + {static} main(args : String[]) : void
+  }
+
+  class Thread {
+    + start() : void
+  }
+
+  class UserContext {
+    - userId : Long
+    + UserContext(userId : Long)
+    + getUserId() : Long
+    + setUserId(userId : Long) : void
+  }
+
+  class UserContextProxy {
+    - {static} userContextHolder : ThreadLocal<UserContext>
+    + {static} set(context : UserContext) : void
+    + {static} get() : UserContext
+    + {static} clear() : void
+  }
+
+  class RequestHandler {
+    - token : String
+    + RequestHandler(token : String)
+    + process() : void
+    - parseToken(token : String) : Long
+  }
+
+  UserContextProxy --> UserContext : manages
+  RequestHandler --> UserContextProxy : uses static
+  RequestHandler --> UserContext : creates
+  APP --> RequestHandler : creates
+  APP --> Thread : starts
+  Thread --> RequestHandler : executes
+
+}
+@enduml