code: private ResponseParseItem parseXMLSignSourceData(String body, String rootNode,
                                                       int indexOfRootNode) {
  
          int signDataStartIndex = indexOfRootNode + rootNode.length() + 1;
  
          String xmlStartNode = "<" + AlipayConstants.RESPONSE_XML_ENCRYPT_NODE_NAME + ">";
          String xmlEndNode = "</" + AlipayConstants.RESPONSE_XML_ENCRYPT_NODE_NAME + ">";
  
          int indexOfSign = body.indexOf(xmlEndNode);
  
          if (indexOfSign < 0) {
  
              return new ResponseParseItem(0, 0, "");
          }
  
          int signDataEndIndex = indexOfSign + xmlEndNode.length();
  
          // 包含xml节点的
          String encryptBizContent = body.substring(signDataStartIndex, signDataEndIndex);
  
          String bizContent = encryptBizContent.substring(xmlStartNode.length(),
              encryptBizContent.length() - xmlEndNode.length());
  
          return new ResponseParseItem(signDataStartIndex, signDataEndIndex, bizContent);
      }
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  @param body
  @param rootNode
  @param indexOfRootNode
  @return