Radu/bael 1265 junit updates (#2965)

* Code for test article: Different Types of Bean Injection in Spring

* Adding jUnits for test article: Different Types of Bean Injection in Spring

* BAEL-1265: Adding jUnit for article

* BAEL-1265: Closing ExecutorService in jUnit

* BAEL-1265: Adding jUnit for CountDownLatch and example for ExecutorService.awaitTermination

core-java-concurrency/src/main/java/com/baeldung/concurrent/executorservice/DelayedCallable.java

@@ -1,11 +1,18 @@
 package com.baeldung.concurrent.executorservice;
 
 import java.util.concurrent.Callable;
+import java.util.concurrent.CountDownLatch;
 
 public class DelayedCallable implements Callable<String> {
     
     private String name;
     private long period;
+    private CountDownLatch latch;
+    
+    public DelayedCallable(String name, long period, CountDownLatch latch) {
+        this(name, period);
+        this.latch = latch;
+    }
 
     public DelayedCallable(String name, long period) {
         this.name = name;
@@ -16,9 +23,15 @@ public class DelayedCallable implements Callable<String> {
 
         try {
             Thread.sleep(period);
+            
+            if (latch != null) {
+                latch.countDown();
+            }
+            
         } catch (InterruptedException ex) {
             // handle exception
             ex.printStackTrace();
+            Thread.currentThread().interrupt();
         }
 
         return name;