Program: 21305
Project: 21305
Buggy source:
private String EinzelLinks(String url){
  String links="String_Node_Str";
  boolean fileDownloaded=false;
  if (!url.startsWith("String_Node_Str")) {
    url="String_Node_Str" + url;
  }
  try {
    url=url.replaceAll("String_Node_Str","String_Node_Str");
    url=url.replaceAll("String_Node_Str","String_Node_Str");
    RequestInfo reqinfo=HTTP.getRequest(new URL(url));
    File captchaFile=null;
    String capTxt=null;
    while (true) {
      reqinfo.setHtmlCode(reqinfo.getHtmlCode().replaceAll("String_Node_Str","String_Node_Str").replaceAll("String_Node_Str","String_Node_Str"));
      Matcher matcher=patternCaptcha.matcher(reqinfo.getHtmlCode());
      if (matcher.find()) {
        if (captchaFile != null && capTxt != null) {
          JDUtilities.appendInfoToFilename(this,captchaFile,capTxt,false);
        }
        String captchaAdress="String_Node_Str" + matcher.group(2);
        captchaFile=Plugin.getLocalCaptchaFile(this,"String_Node_Str");
        fileDownloaded=Browser.download(captchaFile,captchaAdress);
        logger.info("String_Node_Str" + fileDownloaded);
        if (!fileDownloaded || !captchaFile.exists() || captchaFile.length() == 0) {
          logger.severe("String_Node_Str");
          try {
            Thread.sleep(1000);
            reqinfo=HTTP.getRequest(new URL(url));
          }
 catch (          InterruptedException e) {
          }
          continue;
        }
        capTxt=JDUtilities.getCaptcha(this,"String_Node_Str",captchaFile,false);
        reqinfo=HTTP.postRequest(new URL(url),"String_Node_Str" + matcher.group(1) + "String_Node_Str"+ capTxt+ "String_Node_Str");
      }
 else {
        if (captchaFile != null && capTxt != null) {
          JDUtilities.appendInfoToFilename(this,captchaFile,capTxt,true);
          if (useUserinputIfCaptchaUnknown() && getCaptchaDetectionID() == Plugin.CAPTCHA_USER_INPUT && getLastCaptcha() != null && getLastCaptcha().getLetterComperators() != null) {
            LetterComperator[] lcs=getLastCaptcha().getLetterComperators();
            getLastCaptcha().setCorrectcaptchaCode(capTxt.trim());
            if (lcs.length == capTxt.trim().length()) {
              for (int i=0; i < capTxt.length(); i++) {
                if (lcs[i] != null && lcs[i].getDecodedValue() != null && capTxt.substring(i,i + 1).equalsIgnoreCase(lcs[i].getDecodedValue()) && lcs[i].getValityPercent() < 30.0) {
                  logger.severe("String_Node_Str" + i + "String_Node_Str"+ lcs[i].getDecodedValue()+ "String_Node_Str"+ lcs[i].getValityPercent()+ "String_Node_Str"+ capTxt.substring(i,i + 1));
                }
 else {
                  logger.severe("String_Node_Str" + i + "String_Node_Str"+ lcs[i].getDecodedValue()+ "String_Node_Str"+ lcs[i].getValityPercent()+ "String_Node_Str"+ capTxt.substring(i,i + 1));
                  final String character=capTxt.substring(i,i + 1);
                  logger.info("String_Node_Str");
                  Letter letter=lcs[i].getA();
                  String captchaHash=UTILITIES.getLocalHash(captchaFile);
                  letter.setSourcehash(captchaHash);
                  letter.setOwner(getLastCaptcha().owner);
                  letter.setDecodedValue(character);
                  getLastCaptcha().owner.letterDB.add(letter);
                  getLastCaptcha().owner.saveMTHFile();
                }
              }
            }
 else {
              logger.info("String_Node_Str");
            }
          }
        }
        break;
      }
    }
    links=reqinfo.getLocation();
  }
 catch (  IOException e) {
    e.printStackTrace();
  }
  return links;
}

Fixed version (ground truth):
private String EinzelLinks(String url){
  String links="String_Node_Str";
  boolean fileDownloaded=false;
  if (!url.startsWith("String_Node_Str")) {
    url="String_Node_Str" + url;
  }
  try {
    if (!url.matches("String_Node_Str")) {
      url=url.replaceAll("String_Node_Str","String_Node_Str");
      url=url.replaceAll("String_Node_Str","String_Node_Str");
    }
    RequestInfo reqinfo=HTTP.getRequest(new URL(url));
    File captchaFile=null;
    String capTxt=null;
    while (true) {
      reqinfo.setHtmlCode(reqinfo.getHtmlCode().replaceAll("String_Node_Str","String_Node_Str").replaceAll("String_Node_Str","String_Node_Str"));
      Matcher matcher=patternCaptcha.matcher(reqinfo.getHtmlCode());
      if (matcher.find()) {
        if (captchaFile != null && capTxt != null) {
          JDUtilities.appendInfoToFilename(this,captchaFile,capTxt,false);
        }
        String captchaAdress="String_Node_Str" + matcher.group(2);
        captchaFile=Plugin.getLocalCaptchaFile(this,"String_Node_Str");
        fileDownloaded=Browser.download(captchaFile,captchaAdress);
        logger.info("String_Node_Str" + fileDownloaded);
        if (!fileDownloaded || !captchaFile.exists() || captchaFile.length() == 0) {
          logger.severe("String_Node_Str");
          try {
            Thread.sleep(1000);
            reqinfo=HTTP.getRequest(new URL(url));
          }
 catch (          InterruptedException e) {
          }
          continue;
        }
        capTxt=JDUtilities.getCaptcha(this,"String_Node_Str",captchaFile,false);
        reqinfo=HTTP.postRequest(new URL(url),"String_Node_Str" + matcher.group(1) + "String_Node_Str"+ capTxt+ "String_Node_Str");
      }
 else {
        if (captchaFile != null && capTxt != null) {
          JDUtilities.appendInfoToFilename(this,captchaFile,capTxt,true);
          if (useUserinputIfCaptchaUnknown() && getCaptchaDetectionID() == Plugin.CAPTCHA_USER_INPUT && getLastCaptcha() != null && getLastCaptcha().getLetterComperators() != null) {
            LetterComperator[] lcs=getLastCaptcha().getLetterComperators();
            getLastCaptcha().setCorrectcaptchaCode(capTxt.trim());
            if (lcs.length == capTxt.trim().length()) {
              for (int i=0; i < capTxt.length(); i++) {
                if (lcs[i] != null && lcs[i].getDecodedValue() != null && capTxt.substring(i,i + 1).equalsIgnoreCase(lcs[i].getDecodedValue()) && lcs[i].getValityPercent() < 30.0) {
                  logger.severe("String_Node_Str" + i + "String_Node_Str"+ lcs[i].getDecodedValue()+ "String_Node_Str"+ lcs[i].getValityPercent()+ "String_Node_Str"+ capTxt.substring(i,i + 1));
                }
 else {
                  logger.severe("String_Node_Str" + i + "String_Node_Str"+ lcs[i].getDecodedValue()+ "String_Node_Str"+ lcs[i].getValityPercent()+ "String_Node_Str"+ capTxt.substring(i,i + 1));
                  final String character=capTxt.substring(i,i + 1);
                  logger.info("String_Node_Str");
                  Letter letter=lcs[i].getA();
                  String captchaHash=UTILITIES.getLocalHash(captchaFile);
                  letter.setSourcehash(captchaHash);
                  letter.setOwner(getLastCaptcha().owner);
                  letter.setDecodedValue(character);
                  getLastCaptcha().owner.letterDB.add(letter);
                  getLastCaptcha().owner.saveMTHFile();
                }
              }
            }
 else {
              logger.info("String_Node_Str");
            }
          }
        }
        break;
      }
    }
    links=reqinfo.getLocation();
  }
 catch (  IOException e) {
    e.printStackTrace();
  }
  return links;
}