title: How can I check if a resource bundle key does not exist using JSTL tags?
body: <p>I have a resource file that will have some optional keys. If the optional resource key is not present, I set a default instead. It appears that there is no easy way to determine if a key exists in the resource bundle. So this is what I'm doing to get around it. </p>
  
  <pre><code>&lt;fmt:message var="title" key="login.reg.signup.${signupForm.regfrom}.title" /&gt;
  &lt;c:if test='${fn:startsWith(title, "??")}'&gt;
      &lt;fmt:message var="title" key="login.reg.signup.default.title" /&gt; 
  &lt;/c:if&gt;
  </code></pre>
  
  <p>Is there a better way?</p>