Checkmarks - user input from element toByteArray

Question

Getting the below exception in the checkmarks,

Method update at line 108 of com.ibm.vch.vch-*\UpdateServiceImpl.java gets user input from element toByteArray . This element’s value flows through the code without being validated, and is eventually used in a loop condition in updateCustomFieldMapping at line 154 of *\FieldUtils.java. This constitutes an Unchecked Input for Loop Condition.

InputStream activityXML = new JaxbSerializer().marshal(resource.getActivity());
    line--- > 108           byte[] xmlData = IOUtils.toByteArray(activityXML);
                entity.setXmlData(xmlData);

Is there validation i can perform at line 108? Thanks in advance.

Edited :

private static String update**Mapping(String str, Element cusFieldsElement) {
        Pattern p = Pattern.compile(IELD_PATTERN);
        Matcher m = p.matcher(xmlStr);
        while (m.find()) {
            String b = m.group();
            String xPath = b.substring(2, b.length() - 1);
            if (xPath != null) {
                String id = xPath.substring(xPath.lastIndexOf(".") + 1);
                String name = fetchFieldNameFrId(id, cusFieldsElement);
                if (name != null) {
                    String updatedId = "${"
                            + CustomFieldUtils.constructCustomFieldID("/" + Constants.PARAMETERS + "/",
                                    name) + "}";
                    updatedId = StringEscapeUtils.escapeXml10(updatedId);
                    xmlStr = xmlStr.replace(b, updatedId);
                }
            }
        }
        return xmlStr;
    }