title: SpringBoot @SqsListener - not working - with Exception - TaskRejectedException
body: <p>I have a AWS SQS with 5000 messages already on the Queue (Sample Message looks like this 'Hello @ 1')
  I created a SpringBoot Application and inside one of the Component Classes create a method to read messages from the SQS.</p>
  
  <pre><code>package com.example.aws.sqs.service;
  
  import org.springframework.cloud.aws.messaging.listener.SqsMessageDeletionPolicy;
  import org.springframework.cloud.aws.messaging.listener.annotation.SqsListener;
  import org.springframework.stereotype.Component;
  import lombok.extern.slf4j.Slf4j;
  
  @Component
  @Slf4j
  public class MessageReceiverService {   
  
  @SqsListener(value = { "${cloud.aws.sqs.url}" }, deletionPolicy = SqsMessageDeletionPolicy.ALWAYS)
  public void readMessage(String message){
      log.info("Reading Message... {}", message);
  }
  </code></pre>
  
  <p>}</p>
  
  <p>My main SpringBoot Class</p>
  
  <pre><code>@SpringBootApplication 
  public class AwsSqsApplicationConsumer {
  public static void main(String[] args) {
      SpringApplication.run(AwsSqsApplicationConsumer.class, args);
  }
  }
  </code></pre>
  
  <p>Exception I get when the application runs:</p>
  
  <pre><code>s.c.a.m.l.SimpleMessageListenerContainer : An Exception occurred while polling queue '&lt;my sqs name&gt;'. The failing operation will be retried in 10000 milliseconds
  org.springframework.core.task.TaskRejectedException: Executor [java.util.concurrent.ThreadPoolExecutor@7c1594a5[Running, pool size = 3, active threads = 3, queued tasks = 0, completed tasks = 20]] did not accept task: org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer$SignalExecutingRunnable@1cbd9ef2
  at org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor.execute(ThreadPoolTaskExecutor.java:309) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
  at org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer$AsynchronousMessageListener.run(SimpleMessageListenerContainer.java:286) ~[spring-cloud-aws-messaging-2.0.0.RELEASE.jar:2.0.0.RELEASE]
  at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:511) [na:1.8.0_65]
  at java.util.concurrent.FutureTask.run(FutureTask.java:266) [na:1.8.0_65]
  at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) [na:1.8.0_65]
  at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) [na:1.8.0_65]
  at java.lang.Thread.run(Thread.java:745) [na:1.8.0_65]
  Caused by: java.util.concurrent.RejectedExecutionException: Task org.springframework.cloud.aws.messaging.listener.SimpleMessageListenerContainer$SignalExecutingRunnable@1cbd9ef2 rejected from java.util.concurrent.ThreadPoolExecutor@7c1594a5[Running, pool size = 3, active threads = 2, queued tasks = 0, completed tasks = 20]
  at java.util.concurrent.ThreadPoolExecutor$AbortPolicy.rejectedExecution(ThreadPoolExecutor.java:2047) ~[na:1.8.0_65]
  at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:823) [na:1.8.0_65]
  at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1369) [na:1.8.0_65]
  at org.springframework.scheduling.concurrent.ThreadPoolTaskExecutor.execute(ThreadPoolTaskExecutor.java:306) ~[spring-context-5.0.7.RELEASE.jar:5.0.7.RELEASE]
  ... 6 common frames omitted
  </code></pre>
  
  <p>I am NOT configuring any custom Executor services. Using the preconfigured Spring Beans.
  springBootVersion = '2.0.3.RELEASE'
  springCloudVersion = 'Finchley.RELEASE'</p>