[BAEL-6027] Add example for Awaitility and Thread.sleep comparison (#13450)

* Add example for Awaitility and Thread.sleep comparison

* Fix unit test method name and indentation.

* Use property in pom.xml for awaitility dependency version.

---------

Co-authored-by: Uhrin Attila <attila.uhrin@frontendart.com>

core-java-modules/core-java-concurrency-basic-3/src/main/java/com/baeldung/concurrent/RequestProcessor.java

@@ -0,0 +1,35 @@
+package com.baeldung.concurrent;
+
+import java.util.HashMap;
+import java.util.Map;
+import java.util.Random;
+import java.util.UUID;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
+
+public class RequestProcessor {
+
+    private Map<String, String> requestStatuses = new HashMap<>();
+
+    public String processRequest() {
+        String requestId = UUID.randomUUID().toString();
+        requestStatuses.put(requestId, "PROCESSING");
+
+        ScheduledExecutorService executorService = Executors.newSingleThreadScheduledExecutor();
+        executorService.schedule((() -> {
+            requestStatuses.put(requestId, "DONE");
+        }), getRandomNumberBetween(500, 2000), TimeUnit.MILLISECONDS);
+
+        return requestId;
+    }
+
+    public String getStatus(String requestId) {
+        return requestStatuses.get(requestId);
+    }
+
+    private int getRandomNumberBetween(int min, int max) {
+        Random random = new Random();
+        return random.nextInt(max - min) + min;
+    }
+}