code: public String getMimeType(String file) {
  
          if (defaultExternalContext != null) {
              return defaultExternalContext.getMimeType(file);
          }
  
          throw new UnsupportedOperationException();
          
      }
docs: <p class="changed_added_2_0">Returns the MIME type of the
  specified file or <code>null</code> if the MIME type is not
  known.  The MIME type is determined by the container.</p>
  
  <p class="changed_added_2_0">It is valid to call this method
  during application startup or shutdown.  If called during application
  startup or shutdown, this method calls through to the
  <code>getMimeType()</code> method on the same container
  context instance (<code>ServletContext</code> or
  <code>PortletContext</code>) as the one used when calling
  <code>getMimeType()</code> on the
  <code>ExternalContext</code> returned by the
  <code>FacesContext</code> during an actual request.</p>
  
  <div class="changed_added_2_0">
  
  <p><em>Servlet:</em> This must be the value returned by the
  <code>javax.servlet.ServletContext</code> method
  <code>getMimeType()</code>.</p>
  
  </div>
  
  @param file The file for which the mime type should be obtained.
  
  
  @since 2.0