public String getExtraDataExpression() {
    String result = null;
    if (hasExpressionAsExtraData()) {
      result = this.extraData.substring(1, this.extraData.length() - 1);
    }
    return result;
  }
public String getExtraDataExpression ( ) { String result = null ; if ( hasExpressionAsExtraData ( ) ) { result = this . extraData . substring ( 1 , this . extraData . length ( ) - 1 ) ; } return result ; }
Extract expression for extra data.

@return extracted expression from extra data, null if it is not extra data