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