title: How to solve the warning message about "But a callback is not registered (anymore) to process this response" in WSO2 ESB
body: <p>I called HTTP endpoint and get correct response.</p>
  
  <p>But I don't know why the warning message as below in EI log.</p>
  
  <p>How can I do to solve this warning? Thank you.</p>
  
  <pre><code>Synapse received a response for the request with message Id : urn:uuid:f1d3d901-322e-4ac2-ad28-5c4fd3c97aa5 But a callback is not registered (anymore) to process this response
  </code></pre>