code: public static Boolean parseBooleanValue (final String value) {
          if (value == null) return null;
          if (TextKeyword.YES.equals(value)) return true;
          if (TextKeyword.NO.equals(value)) return false;
          return null;
      }
docs: A methods for parsing boolean values from the <i>value</i> part of a <i>key=value</i> pair String. If
  <i>value</i> equals <i>"Yes"</i>, then <code>true</code> will be returned, if <i>value</i> equals <i>"No"</i>,
  then <code>false</code> will be returned. In all other cases the method will return <code>null</code>.
  
  @param value a String containing
  @return <code>true</code>, <code>false</code>, or <code>null</code>