code: protected org.javalite.activeweb.FileItem getFile(String fieldName, List<FormItem> formItems){
          for (FormItem formItem : formItems) {
              if(formItem instanceof org.javalite.activeweb.FileItem && formItem.getFieldName().equals(fieldName)){
                  return (org.javalite.activeweb.FileItem)formItem;
              }
          }
          return null;
      }
docs: Convenience method to get file content from <code>multipart/form-data</code> request. If more than one files with the same
  name are submitted, only one is returned.
  
  @param fieldName name of form field from the  <code>multipart/form-data</code> request corresponding to the uploaded file.
  @param formItems form items retrieved from <code>multipart/form-data</code> request.
  @return <code>InputStream</code> from which to read content of uploaded file or null if FileItem with this name is not found.