title: Why use the j_username and SPRING_SECURITY_LAST_USERNAME variables?
body: <p>Why do this?</p>
  
  <pre><code>&lt;input type="text" name="j_username" value="${SPRING_SECURITY_LAST_USERNAME}"&gt;
  </code></pre>
  
  <p>instead of this?</p>
  
  <pre><code>&lt;input type="text" name="username" value=""&gt;
  </code></pre>
  
  <p>What's the value of the j_username and SPRING_SECURITY_LAST_USERNAME variables?</p>