code: protected void setNullText(String nullText) {
          if (nullText == null) {
              nullText = StringUtils.EMPTY;
          }
          this.nullText = nullText;
      }
docs: <p>Sets the text to output when <code>null</code> found.</p>
  
  <p><code>null</code> is accepted, but will be converted to
  an empty String.</p>
  
  @param nullText  the new text to output when null found