[JAVA-17295] Create and initialize ThreadPoolTaskExecutor (#13249)

Co-authored-by: panagiotiskakos <panagiotis.kakos@libra-is.com>

spring-scheduling/src/main/java/com/baeldung/async/config/SpringAsyncConfig.java

@@ -24,7 +24,9 @@ public class SpringAsyncConfig implements AsyncConfigurer {
 
     @Override
     public Executor getAsyncExecutor() {
-        return new SimpleAsyncTaskExecutor();
+        ThreadPoolTaskExecutor threadPoolTaskExecutor = new ThreadPoolTaskExecutor();
+        threadPoolTaskExecutor.initialize();
+        return threadPoolTaskExecutor;
     }
 
     @Override