thread pools examples (#2400)

* thread pools examples

* add logs

guest/thread-pools/src/main/java/com/stackify/services/EmployeeService.java

@@ -0,0 +1,9 @@
+package com.stackify.services;
+
+import com.stackify.models.Employee;
+
+public class EmployeeService {
+    public double calculateBonus(Employee employee) {
+        return 0.1 * employee.getSalary();
+    }
+}