Though its a very old post and I'm not claiming that the answer I am providing is perfect but it served my purpose. So I am keeping this code I wrote using stack to get the data in a way was required in my case. I hope it may be helpful for others.
try (BufferedReader br = new BufferedReader(new FileReader(new File(
                fileName)))) {
            while ((line = br.readLine()) != null) {
                line = line.trim();
                int startOfTag = line.indexOf("<");
                int endOfTag = line.indexOf(">");
                String currentTag = "";
                if (startOfTag > -1 && endOfTag > -1) {
                    if (countStart)
                        headerTagsCounter++;
                    currentTag = line.substring(startOfTag + 1, endOfTag);
                    String currentData = line.substring(endOfTag + 1,
                            line.length());
                    if (i == 1) {
                        tagStack.push(currentTag);
                        i++;
                    }
                    if (currentData.isEmpty() || currentData == "") {//If there is no data, its a parent tag...
                        if (!currentTag.contains("/")) {// if its an opening tag...
                            switch (currentTag) {// these tags are useless in my case, so just skipping these tags.
                            case "CORRECTION":
                            case "PAPER":
                            case "PRIVATE-TO-PUBLIC":
                            case "DELETION":
                            case "CONFIRMING-COPY":
                            case "CAPTION":
                            case "STUB":
                            case "COLUMN":
                            case "TABLE-FOOTNOTES-SECTION":
                            case "FOOTNOTES":
                            case "PAGE":
                                break;
                            default: {
                                countStart = false;
                                int tagCounterNumber = 0;
                                String historyTagToRemove = "";
                                for (String historyTag : historyStack) {
                                    String tagCounter = "";
                                    if (historyTag.contains(currentTag)) {//if it's  a repeating tag..Append the counter  and update the same  in history tag..
                                        historyTagToRemove = historyTag;
                                        if (historyTag
                                                .equalsIgnoreCase(currentTag)) {
                                            tagCounterNumber = 1;
                                        } else if (historyTag.length() > currentTag
                                                .length()) {
                                            tagCounter = historyTag
                                                    .substring(currentTag
                                                            .length());
                                            if (tagCounter != null
                                                    && !tagCounter.isEmpty()) {
                                                tagCounterNumber = Integer
                                                        .parseInt(tagCounter) + 1;
                                            }
                                        }
                                    }
                                }
                                if (tagCounterNumber > 0)
                                    currentTag += tagCounterNumber;
                                if (historyTagToRemove != null
                                        && !historyTagToRemove.isEmpty()) {
                                    historyStack.remove(historyTagToRemove);
                                    historyStack.push(currentTag);
                                }
                                tagStack.push(currentTag);
                                break;
                            }
                            }
                        } else// if its end of a tag... Match the current tag with top of stack and if its a match, pop  it out
                        {
                            currentTag = currentTag.substring(1);
                            String tagRemoved = "";
                            String topStackTag = tagStack.lastElement();
                            if (topStackTag.contains(currentTag)) {
                                tagRemoved = tagStack.pop();
                                historyStack.push(tagRemoved);
                            }
                            if (tagStack.size() < 2)
                                cik = "";
                            if (tagStack.size() == 2 && cik != null
                                    && !cik.isEmpty())
                                for (int j = headerTagsCounter - 1; j < tagList.size(); j++) {
                                    String item = tagList.get(j);
                                    if (!item.contains("@@")) {
                                        item += "@@" + cik;
                                        tagList.remove(j);
                                        tagList.add(j, item);
                                    }
                                }
                        }
                    } else {// if current tag has some data...
                        currentData = currentData.trim();
                        String stackValue = "";
                        for (String tag : tagStack) {
                            if (stackValue != null && !stackValue.isEmpty()
                                    && stackValue != "")
                                stackValue = stackValue + "||" + tag;
                            else
                                stackValue = tag;
                        }
                        switch (currentTag) {
                        case "ACCESSION-NUMBER":
                            accessionNumber = currentData;
                            break;
                        case "FILING-DATE":
                            dateFiled = currentData;
                            break;
                        case "TYPE":
                            formType = currentData;
                            break;
                        case "CIK":
                            cik = currentData;
                            break;
                        }
                        tagList.add(stackValue + "$$" + currentTag + "::"+ currentData);
                    }
                }
            }
// Now all your data is available with in tagList, stack is separated by ||,  key is separated by $$ and value is separated by ::
            }
        } catch (Exception e) {
            // TODO Auto-generated catch block
        }
    }
Output: 
Source of file:  http://10k-staging.s3.amazonaws.com/edgar0105/2016/12/20/935015/000119312516799070/0001193125-16-799070.hdr.sgml
Output of code:
SEC-HEADER$$SEC-HEADER::0001193125-16-799070.hdr.sgml : 20161220
SEC-HEADER$$ACCEPTANCE-DATETIME::20161220172458
SEC-HEADER$$ACCESSION-NUMBER::0001193125-16-799070
SEC-HEADER$$TYPE::485APOS
SEC-HEADER$$PUBLIC-DOCUMENT-COUNT::9
SEC-HEADER$$FILING-DATE::20161220
SEC-HEADER$$DATE-OF-FILING-DATE-CHANGE::20161220
SEC-HEADER||FILER||COMPANY-DATA$$CONFORMED-NAME::ARTISAN PARTNERS FUNDS INC@@0000935015
SEC-HEADER||FILER||COMPANY-DATA$$CIK::0000935015@@0000935015
SEC-HEADER||FILER||COMPANY-DATA$$IRS-NUMBER::391811840@@0000935015
SEC-HEADER||FILER||COMPANY-DATA$$STATE-OF-INCORPORATION::WI@@0000935015
SEC-HEADER||FILER||COMPANY-DATA$$FISCAL-YEAR-END::0930@@0000935015
SEC-HEADER||FILER||FILING-VALUES$$FORM-TYPE::485APOS@@0000935015
SEC-HEADER||FILER||FILING-VALUES$$ACT::33@@0000935015
SEC-HEADER||FILER||FILING-VALUES$$FILE-NUMBER::033-88316@@0000935015
SEC-HEADER||FILER||FILING-VALUES$$FILM-NUMBER::162062197@@0000935015
SEC-HEADER||FILER||BUSINESS-ADDRESS$$STREET1::875 EAST WISCONSIN AVE STE 800@@0000935015
SEC-HEADER||FILER||BUSINESS-ADDRESS$$CITY::MILWAUKEE@@0000935015
SEC-HEADER||FILER||BUSINESS-ADDRESS$$STATE::WI@@0000935015
SEC-HEADER||FILER||BUSINESS-ADDRESS$$ZIP::53202@@0000935015
SEC-HEADER||FILER||BUSINESS-ADDRESS$$PHONE::414-390-6100@@0000935015
SEC-HEADER||FILER||MAIL-ADDRESS$$STREET1::875 EAST WISCONSIN AVE STE 800@@0000935015
SEC-HEADER||FILER||MAIL-ADDRESS$$CITY::MILWAUKEE@@0000935015
SEC-HEADER||FILER||MAIL-ADDRESS$$STATE::WI@@0000935015
SEC-HEADER||FILER||MAIL-ADDRESS$$ZIP::53202@@0000935015
SEC-HEADER||FILER||FORMER-COMPANY$$FORMER-CONFORMED-NAME::ARTISAN FUNDS INC@@0000935015
SEC-HEADER||FILER||FORMER-COMPANY$$DATE-CHANGED::19950310@@0000935015
SEC-HEADER||FILER||FORMER-COMPANY1$$FORMER-CONFORMED-NAME::ZIEGLER FUNDS INC@@0000935015
SEC-HEADER||FILER||FORMER-COMPANY1$$DATE-CHANGED::19950109@@0000935015
SEC-HEADER||FILER1||COMPANY-DATA1$$CONFORMED-NAME::ARTISAN PARTNERS FUNDS INC@@0000935015
SEC-HEADER||FILER1||COMPANY-DATA1$$CIK::0000935015@@0000935015
SEC-HEADER||FILER1||COMPANY-DATA1$$IRS-NUMBER::391811840@@0000935015
SEC-HEADER||FILER1||COMPANY-DATA1$$STATE-OF-INCORPORATION::WI@@0000935015
SEC-HEADER||FILER1||COMPANY-DATA1$$FISCAL-YEAR-END::0930@@0000935015
SEC-HEADER||FILER1||FILING-VALUES1$$FORM-TYPE::485APOS@@0000935015
SEC-HEADER||FILER1||FILING-VALUES1$$ACT::40@@0000935015
SEC-HEADER||FILER1||FILING-VALUES1$$FILE-NUMBER::811-08932@@0000935015
SEC-HEADER||FILER1||FILING-VALUES1$$FILM-NUMBER::162062198@@0000935015
SEC-HEADER||FILER1||BUSINESS-ADDRESS1$$STREET1::875 EAST WISCONSIN AVE STE 800@@0000935015
SEC-HEADER||FILER1||BUSINESS-ADDRESS1$$CITY::MILWAUKEE@@0000935015
SEC-HEADER||FILER1||BUSINESS-ADDRESS1$$STATE::WI@@0000935015
SEC-HEADER||FILER1||BUSINESS-ADDRESS1$$ZIP::53202@@0000935015
SEC-HEADER||FILER1||BUSINESS-ADDRESS1$$PHONE::414-390-6100@@0000935015
SEC-HEADER||FILER1||MAIL-ADDRESS1$$STREET1::875 EAST WISCONSIN AVE STE 800@@0000935015
SEC-HEADER||FILER1||MAIL-ADDRESS1$$CITY::MILWAUKEE@@0000935015
SEC-HEADER||FILER1||MAIL-ADDRESS1$$STATE::WI@@0000935015
SEC-HEADER||FILER1||MAIL-ADDRESS1$$ZIP::53202@@0000935015
SEC-HEADER||FILER1||FORMER-COMPANY2$$FORMER-CONFORMED-NAME::ARTISAN FUNDS INC@@0000935015
SEC-HEADER||FILER1||FORMER-COMPANY2$$DATE-CHANGED::19950310@@0000935015
SEC-HEADER||FILER1||FORMER-COMPANY3$$FORMER-CONFORMED-NAME::ZIEGLER FUNDS INC@@0000935015
SEC-HEADER||FILER1||FORMER-COMPANY3$$DATE-CHANGED::19950109@@0000935015
SEC-HEADER||SERIES-AND-CLASSES-CONTRACTS-DATA||NEW-SERIES-AND-CLASSES-CONTRACTS$$OWNER-CIK::0000935015
SEC-HEADER||SERIES-AND-CLASSES-CONTRACTS-DATA||NEW-SERIES-AND-CLASSES-CONTRACTS||NEW-SERIES$$SERIES-ID::S000056665
SEC-HEADER||SERIES-AND-CLASSES-CONTRACTS-DATA||NEW-SERIES-AND-CLASSES-CONTRACTS||NEW-SERIES$$SERIES-NAME::Artisan Thematic Fund
SEC-HEADER||SERIES-AND-CLASSES-CONTRACTS-DATA||NEW-SERIES-AND-CLASSES-CONTRACTS||NEW-SERIES||CLASS-CONTRACT$$CLASS-CONTRACT-ID::C000179292
SEC-HEADER||SERIES-AND-CLASSES-CONTRACTS-DATA||NEW-SERIES-AND-CLASSES-CONTRACTS||NEW-SERIES||CLASS-CONTRACT$$CLASS-CONTRACT-NAME::Investor Shares