title: Why is this StringTemplates with custom delimiters not working?
body: <p>I'm trying to use String Template with custom delimiters.</p>
  
  <p>This code snippet:</p>
  
  <pre><code>new ST("Hello @what@", '@', '@').add("what", "world").render()
  </code></pre>
  
  <p>throws <code>org.stringtemplate.v4.compiler.STException</code>, so I'm obviously doing it wrong.</p>
  
  <p>If I change it to <code>new ST("Hello $what$", '$', '$')</code>, it works. Why is <code>@</code> not working?</p>
  
  <p><strong>Edit</strong> - I tried other characters besides <code>$</code> and <code>@</code>, and nothing but <code>$</code> works so far. What's going on?</p>