Program: 20887
Project: 20887
Buggy source:
@Override public void handlePremium(DownloadLink link,Account account) throws Exception {
  String passCode=null;
  requestFileInformation(link);
  login(account);
  br.setCookie(COOKIE_HOST,"String_Node_Str","String_Node_Str");
  br.setFollowRedirects(false);
  br.getPage(link.getDownloadURL());
  if (nopremium) {
    doFree(link);
  }
 else {
    String dllink=br.getRedirectLocation();
    if (dllink == null) {
      doSomething();
      Form DLForm=br.getFormbyProperty("String_Node_Str","String_Node_Str");
      if (DLForm == null)       throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
      if (brbefore.contains(passwordText)) {
        passCode=handlePassword(passCode,DLForm,link);
      }
      br.submitForm(DLForm);
      dllink=br.getRedirectLocation();
      if (dllink == null) {
        checkErrors(link,true,passCode);
        if (dllink == null) {
          dllink=new Regex(brbefore,"String_Node_Str").getMatch(0);
          if (dllink == null) {
            dllink=new Regex(brbefore,"String_Node_Str").getMatch(1);
            if (dllink == null) {
              dllink=new Regex(brbefore,"String_Node_Str").getMatch(0);
            }
          }
        }
      }
    }
    if (dllink == null) {
      logger.warning("String_Node_Str");
      throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    }
    logger.info("String_Node_Str" + dllink + "String_Node_Str");
    jd.plugins.BrowserAdapter.openDownload(br,link,dllink,true,0);
    if (passCode != null) {
      link.setProperty("String_Node_Str",passCode);
    }
    boolean error=false;
    try {
      if (dl.getConnection().getContentType() != null && dl.getConnection().getContentType().contains("String_Node_Str")) {
        error=true;
      }
    }
 catch (    Exception e) {
      error=true;
    }
    if (error == true) {
      logger.warning("String_Node_Str");
      br.followConnection();
      checkServerErrors();
      throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    }
    dl.startDownload();
  }
}

Fixed version (ground truth):
@Override public void handlePremium(DownloadLink link,Account account) throws Exception {
  String passCode=null;
  requestFileInformation(link);
  login(account);
  br.setCookie(COOKIE_HOST,"String_Node_Str","String_Node_Str");
  br.setFollowRedirects(false);
  br.getPage(link.getDownloadURL());
  if (nopremium) {
    doFree(link);
  }
 else {
    String dllink=br.getRedirectLocation();
    if (dllink == null) {
      doSomething();
      Form DLForm=br.getFormbyProperty("String_Node_Str","String_Node_Str");
      if (DLForm == null)       throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
      if (brbefore.contains(passwordText)) {
        passCode=handlePassword(passCode,DLForm,link);
      }
      br.submitForm(DLForm);
      dllink=br.getRedirectLocation();
      if (dllink == null) {
        checkErrors(link,true,passCode);
        if (dllink == null) {
          dllink=new Regex(brbefore,"String_Node_Str").getMatch(0);
          if (dllink == null) {
            dllink=new Regex(brbefore,"String_Node_Str").getMatch(1);
            if (dllink == null) {
              dllink=new Regex(brbefore,"String_Node_Str").getMatch(0);
            }
          }
        }
      }
    }
    if (dllink == null) {
      logger.warning("String_Node_Str");
      throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    }
    logger.info("String_Node_Str" + dllink + "String_Node_Str");
    dl=jd.plugins.BrowserAdapter.openDownload(br,link,dllink,true,0);
    if (passCode != null) {
      link.setProperty("String_Node_Str",passCode);
    }
    if (dl.getConnection().getContentType() != null && dl.getConnection().getContentType().contains("String_Node_Str")) {
      logger.warning("String_Node_Str");
      br.followConnection();
      checkServerErrors();
      throw new PluginException(LinkStatus.ERROR_PLUGIN_DEFECT);
    }
    dl.startDownload();
  }
}