Program: 21203
Project: 21203
Buggy source:
@Override public void handleFree(DownloadLink downloadLink) throws Exception {
  if (!getFileInformation(downloadLink)) {
    throw new PluginException(LinkStatus.ERROR_FILE_NOT_FOUND);
  }
  captchaCode=null;
  String steplink=br.getRegex("String_Node_Str").getMatch(0);
  if (steplink == null) {
    downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    if (downloadurl == null) {
      downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    }
    if (downloadurl == null) {
      downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    }
    if (downloadurl == null) {
      throw new PluginException(LinkStatus.ERROR_FATAL);
    }
  }
 else {
    downloadurl="String_Node_Str" + steplink;
    br.getPage(downloadurl);
    if (br.getRedirectLocation() != null) {
      downloadurl=br.getRedirectLocation();
      br.getPage(downloadurl);
    }
    Form capform=br.getFormbyName("String_Node_Str");
    if (capform != null) {
      BufferedImage image=getCSSCaptchaImage(capform.getHtmlCode());
      captchaFile=getLocalCaptchaFile(this);
      ImageIO.write(image,"String_Node_Str",captchaFile);
      captchaCode=Plugin.getCaptchaCode(this,"String_Node_Str",captchaFile,false,downloadLink);
      capform.setVariable(0,captchaCode);
      downloadurl="String_Node_Str" + steplink + "String_Node_Str"+ captchaCode;
      br.getPage(downloadurl);
      if (br.getRedirectLocation() != null && br.getRedirectLocation().contains("String_Node_Str")) {
        throw new PluginException(LinkStatus.ERROR_CAPTCHA);
      }
    }
    steplink=br.getRegex("String_Node_Str").getMatch(0);
    if (steplink == null) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
    downloadurl="String_Node_Str" + steplink;
    br.getPage(downloadurl);
    if (br.getRedirectLocation() == null || br.getRedirectLocation().contains("String_Node_Str")) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
    downloadurl=br.getRedirectLocation();
    if (downloadurl == null) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
  }
  downloadurl=downloadurl.replaceAll("String_Node_Str","String_Node_Str");
  br.setFollowRedirects(true);
  br.setDebug(true);
  dl=br.openDownload(downloadLink,downloadurl,false,1);
  if (dl.getConnection().getContentType().contains("String_Node_Str")) {
    dl.getConnection().disconnect();
    throw new PluginException(LinkStatus.ERROR_FATAL,"String_Node_Str");
  }
  dl.startDownload();
}

Fixed version (ground truth):
@Override public void handleFree(DownloadLink downloadLink) throws Exception {
  if (!getFileInformation(downloadLink)) {
    throw new PluginException(LinkStatus.ERROR_FILE_NOT_FOUND);
  }
  captchaCode=null;
  String steplink=br.getRegex("String_Node_Str").getMatch(0);
  if (steplink == null) {
    downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    if (downloadurl == null) {
      downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    }
    if (downloadurl == null) {
      downloadurl=br.getRegex("String_Node_Str").getMatch(0);
    }
    if (downloadurl == null) {
      throw new PluginException(LinkStatus.ERROR_FATAL);
    }
  }
 else {
    downloadurl="String_Node_Str" + steplink;
    br.getPage(downloadurl);
    if (br.getRedirectLocation() != null) {
      downloadurl=br.getRedirectLocation();
      br.getPage(downloadurl);
    }
    Form capform=br.getFormbyName("String_Node_Str");
    if (capform != null) {
      BufferedImage image=getCSSCaptchaImage(capform.getHtmlCode());
      captchaFile=getLocalCaptchaFile(this);
      captchaFile.mkdirs();
      ImageIO.write(image,"String_Node_Str",captchaFile);
      captchaCode=Plugin.getCaptchaCode(this,"String_Node_Str",captchaFile,false,downloadLink);
      capform.setVariable(0,captchaCode);
      downloadurl="String_Node_Str" + steplink + "String_Node_Str"+ captchaCode;
      br.getPage(downloadurl);
      if (br.getRedirectLocation() != null && br.getRedirectLocation().contains("String_Node_Str")) {
        throw new PluginException(LinkStatus.ERROR_CAPTCHA);
      }
    }
    steplink=br.getRegex("String_Node_Str").getMatch(0);
    if (steplink == null) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
    downloadurl="String_Node_Str" + steplink;
    br.getPage(downloadurl);
    if (br.getRedirectLocation() == null || br.getRedirectLocation().contains("String_Node_Str")) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
    downloadurl=br.getRedirectLocation();
    if (downloadurl == null) {
      throw new PluginException(LinkStatus.ERROR_RETRY);
    }
  }
  downloadurl=downloadurl.replaceAll("String_Node_Str","String_Node_Str");
  br.setFollowRedirects(true);
  br.setDebug(true);
  dl=br.openDownload(downloadLink,downloadurl,false,1);
  if (dl.getConnection().getContentType().contains("String_Node_Str")) {
    dl.getConnection().disconnect();
    throw new PluginException(LinkStatus.ERROR_FATAL,"String_Node_Str");
  }
  dl.startDownload();
}