title: sealing violation: package oracle.net.ns is sealed
body: <p>I am trying to connect to an Oracle 11g XE databse using Oracle SQL Developer. However, I am getting the following exception:</p>
  
  <pre><code>java.lang.SecurityException: sealing violation: package oracle.jdbc.driver is sealed
  </code></pre>
  
  <p>I have searched for an answer on the web, but have not found a solution.</p>
  
  <p>What is causing this and how can I fix it?</p>