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