title: How do exception messages in Thrift exceptions work?
body: <p>I thrift IDL files you can define your own exception types that a service method may throw: </p>
  
  <pre><code>exception SampleException {
      1: list&lt;string&gt; failed
  }
  </code></pre>
  
  <p>Whats the contract for seeing a proper exception message in the logs? I have seen log messages like this: <code>Unhandled exception in foo.bar.Service
  my.package.SomeException: null</code>. I guess where it says <code>null</code> this should be the exception message? </p>
  
  <p>Unfortunately exceptions are not very well documented. Should I be adding a <code>string message</code> field for that to work? Is there any other convertion like name of the field?</p>