title: IncompatibleClassChangeError with Eclipse Jetty
body: <p>I am getting the following error when I try to build a project that uses Eclipse Jetty libraries</p>
  
  <pre><code>java.lang.IncompatibleClassChangeError: 
    class org.eclipse.jetty.server.AbstractConnector has interface 
    org.eclipse.jetty.http.HttpBuffers as super class
  </code></pre>
  
  <p>The specific Eclipse Jetty libraries I am using are:</p>
  
  <pre><code>'org.eclipse.jetty:jetty-websocket:8.1.7.v20120910',
  'org.eclipse.jetty:jetty-client:8.1.7.v20120910'
  </code></pre>
  
  <p>What is the cause of the error and how do I fix it?</p>
  
  <p>Thanks.</p>