title: Cannot convert abcdefg of type class java.lang.String to class [Ljava.lang.String;
body: <p>I'm trying to put together a String in a tag-library like this:</p>
  
  <pre><code>&lt;c:set var="columnText" value="${fn:join(columnText,'.pdf')}" /&gt;
  &lt;a href="${fn:join('http://host:8082/pdf/',columnText)}" &gt;bla&lt;/a&gt;
  </code></pre>
  
  <p>However this exception occurs:</p>
  
  <blockquote>
    <p>javax.el.ELException: Cannot convert abcedfg of type class java.lang.String to class [Ljava.lang.String;</p>
  </blockquote>
  
  <p>'abcdefg' is the content of columnText at first.</p>