title: JSP EL String concatenation
body: <p>How do I concatenate strings in EL?</p>
  
  <p>I want to do something like this but it doesn't work:</p>
  
  <pre><code>${var1 == 0 ? 'hi' : 'hello ' + var2}
  </code></pre>
  
  <p>It throws an exception trying to cast <code>'hello'</code> to a <code>Double</code></p>