title: The method isEmpty(String) is undefined for the type StringUtils
body: <p>When I am trying to use <code>isEmpty()</code>, I am getting the following error.</p>
  
  <blockquote>
    <p>The method isEmpty(String) is undefined for the type StringUtils</p>
  </blockquote>
  
  <p>I am using Java 7, Eclipse Juno.</p>
  
  <p>I manually added the Spring core-3.1.1 jar file too. But no luck.</p>
  
  <p>Can someone please tell me what I am missing?</p>