title: Hystrix does not throw HystrixRuntimeException, and instead empty message error
body: <p>I use Hystrix (version Camden.SR7 of <code>spring-cloud-dependencies</code>) in spring-boot app on service layer without fallback methods. One of service's method looks like the following:</p>
  
  <pre><code>@HystrixCommand(commandKey = "prefs",
          commandProperties = { @HystrixProperty(name = "execution.isolation.thread.timeoutInMilliseconds", value = "2000")})
  @Override
  public void savePrefs(PrefsRequestParams requestParams) throws Exception {
      ...
  }
  </code></pre>
  
  <p>If such method executes longer than 2 seconds, Hystrix will throw java.util.concurrent.TimeoutException: null, and REST response will look like:</p>
  
  <pre><code>{
      "timestamp": 1509452672714,
      "status": 500,
      "error": "Internal Server Error",
      "exception": "java.util.concurrent.TimeoutException",
      "message": "No message available",
      "path": "/prefs"
  }
  </code></pre>
  
  <p>With such response it's unclear from which method exception actually was thrown. If I change <code>spring-cloud-dependencies</code> version to Brixton.SR5 (previous version), it returns clear response:</p>
  
  <pre><code>{
      "timestamp": 1509452426819,
      "status": 500,
      "error": "Internal Server Error",
      "exception": "com.netflix.hystrix.exception.HystrixRuntimeException",
      "message": "prefs timed-out and fallback failed.",
      "path": "/prefs"
  }
  </code></pre>
  
  <p><strong>So new version of Hystrix (actually new version of  spring-cloud-dependencies) does not throw HystrixRuntimeException. Is it a bug or should I configure Hystrix in another way to receive clear message error?</strong></p>
  
  <p>I use the following maven dependencies:</p>
  
  <pre><code>&lt;dependency&gt;
      &lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
      &lt;artifactId&gt;spring-cloud-starter-hystrix&lt;/artifactId&gt;
      &lt;version&gt;1.2.7.RELEASE&lt;/version&gt;
  &lt;/dependency&gt;
  
  &lt;dependencyManagement&gt;
      &lt;dependencies&gt;
          &lt;dependency&gt;
              &lt;groupId&gt;org.springframework.cloud&lt;/groupId&gt;
              &lt;artifactId&gt;spring-cloud-dependencies&lt;/artifactId&gt;
              &lt;version&gt;Camden.SR7&lt;/version&gt;
              &lt;type&gt;pom&lt;/type&gt;
              &lt;scope&gt;import&lt;/scope&gt;
          &lt;/dependency&gt;
       ...
  </code></pre>
  
  <p>from maven dependency tree I see that it uses <code>com.netflix.hystrix:hystrix-core:jar:1.5.6:compile</code> for <code>spring-cloud-dependencies</code> version Camden.SR7,
  and for version Brixton.SR5 - <code>com.netflix.hystrix:hystrix-core:jar:1.5.3:compile</code>.</p>