Program: 17826
Project: 17826
Buggy source:
private Map<String,List<String>> parseRequestHeaders(final Scanner scanner) throws BatchException {
  Map<String,List<String>> headers=new HashMap<String,List<String>>();
  while (scanner.hasNext() && !scanner.hasNext(REG_EX_BLANK_LINE)) {
    if (scanner.hasNext(REG_EX_HEADER)) {
      scanner.next(REG_EX_HEADER);
      currentLineNumber++;
      MatchResult result=scanner.match();
      if (result.groupCount() == 2) {
        String headerName=result.group(1).trim().toLowerCase();
        String headerValue=result.group(2).trim();
        if (HttpHeaders.ACCEPT.equalsIgnoreCase(headerName)) {
          List<String> acceptHeaders=parseAcceptHeaders(headerValue);
          headers.put(headerName,acceptHeaders);
        }
 else         if (HttpHeaders.ACCEPT_LANGUAGE.equalsIgnoreCase(headerName)) {
          List<String> acceptLanguageHeaders=parseAcceptableLanguages(headerValue);
          headers.put(headerName,acceptLanguageHeaders);
        }
 else         if (!BatchConstants.HTTP_CONTENT_ID.equalsIgnoreCase(headerName)) {
          if (headers.containsKey(headerName)) {
            headers.get(headerName).add(headerValue);
          }
 else {
            List<String> headerList=new ArrayList<String>();
            headerList.add(headerValue);
            headers.put(headerName,headerList);
          }
        }
 else {
          List<String> headerList=new ArrayList<String>();
          headerList.add(headerValue);
          headers.put(BatchConstants.REQUEST_HEADER_CONTENT_ID.toLowerCase(),headerList);
        }
      }
    }
 else {
      currentLineNumber++;
      throw new BatchException(BatchException.INVALID_HEADER.addContent(scanner.next()).addContent(currentLineNumber));
    }
  }
  return headers;
}

Fixed version (ground truth):
private Map<String,List<String>> parseRequestHeaders(final Scanner scanner) throws BatchException {
  Map<String,List<String>> headers=new HashMap<String,List<String>>();
  while (scanner.hasNext() && !scanner.hasNext(REG_EX_BLANK_LINE)) {
    if (scanner.hasNext(REG_EX_HEADER)) {
      scanner.next(REG_EX_HEADER);
      currentLineNumber++;
      MatchResult result=scanner.match();
      if (result.groupCount() == 2) {
        String headerName=result.group(1).trim().toLowerCase(Locale.ENGLISH);
        String headerValue=result.group(2).trim();
        if (HttpHeaders.ACCEPT.equalsIgnoreCase(headerName)) {
          List<String> acceptHeaders=parseAcceptHeaders(headerValue);
          headers.put(headerName,acceptHeaders);
        }
 else         if (HttpHeaders.ACCEPT_LANGUAGE.equalsIgnoreCase(headerName)) {
          List<String> acceptLanguageHeaders=parseAcceptableLanguages(headerValue);
          headers.put(headerName,acceptLanguageHeaders);
        }
 else         if (!BatchConstants.HTTP_CONTENT_ID.equalsIgnoreCase(headerName)) {
          if (headers.containsKey(headerName)) {
            headers.get(headerName).add(headerValue);
          }
 else {
            List<String> headerList=new ArrayList<String>();
            headerList.add(headerValue);
            headers.put(headerName,headerList);
          }
        }
 else {
          List<String> headerList=new ArrayList<String>();
          headerList.add(headerValue);
          headers.put(BatchConstants.REQUEST_HEADER_CONTENT_ID.toLowerCase(Locale.ENGLISH),headerList);
        }
      }
    }
 else {
      currentLineNumber++;
      throw new BatchException(BatchException.INVALID_HEADER.addContent(scanner.next()).addContent(currentLineNumber));
    }
  }
  return headers;
}