Program: 7068
Project: 7068
Buggy source:
public void service(String id,String start,String response,String done,PrintWriter writer){
  SlaveBrowser browser=browsers.getBrowser(id);
  if (browser != null) {
    browser.heartBeat();
    if (response != null && browser.isCommandRunning()) {
      Response res=gson.fromJson(response,Response.class);
      if (res.getResponse().contains("String_Node_Str")) {
        LoadedFiles loadedFiles=gson.fromJson(res.getResponse(),LoadedFiles.class);
        Collection<FileResult> allLoadedFiles=loadedFiles.getLoadedFiles();
        if (!allLoadedFiles.isEmpty()) {
          LinkedHashSet<FileInfo> fileInfos=new LinkedHashSet<FileInfo>();
          Collection<FileSource> errorFiles=new LinkedHashSet<FileSource>();
          for (          FileResult fileResult : allLoadedFiles) {
            FileSource fileSource=fileResult.getFileSource();
            if (fileResult.isSuccess()) {
              String filePath=fileSource.getFileSrc();
              fileInfos.add(new FileInfo(fileSource.getBasePath(),fileSource.getTimestamp(),false,false,null));
            }
 else {
              errorFiles.add(fileSource);
            }
          }
          browser.addFiles(fileInfos);
          if (errorFiles.size() > 0) {
            browser.removeFiles(errorFiles);
          }
        }
        forwardingMapper.clear();
      }
      boolean isLast=done != null;
      browser.addResponse(response,isLast);
      if (!isLast) {
        writer.print(NOOP);
        writer.flush();
        return;
      }
    }
    Command command=null;
    if (start != null) {
      browser.resetFileSet();
      urlTranslator.clear();
      Command commandRunning=browser.getCommandRunning();
      if (commandRunning != null) {
        JsonCommand jsonCommand=gson.fromJson(commandRunning.getCommand(),JsonCommand.class);
        if (jsonCommand.getCommand().equals(JsonCommand.CommandType.RESET.getCommand())) {
          command=browser.getLastDequeuedCommand();
        }
      }
    }
 else {
      command=browser.dequeueCommand();
    }
    writer.print(command != null ? command.getCommand() : NOOP);
  }
  writer.flush();
}

Fixed version (ground truth):
public void service(String id,String start,String response,String done,PrintWriter writer){
  SlaveBrowser browser=browsers.getBrowser(id);
  if (browser != null) {
    browser.heartBeat();
    if (response != null && browser.isCommandRunning()) {
      Response res=gson.fromJson(response,Response.class);
      if (res.getResponse().contains("String_Node_Str")) {
        LoadedFiles loadedFiles=gson.fromJson(res.getResponse(),LoadedFiles.class);
        Collection<FileResult> allLoadedFiles=loadedFiles.getLoadedFiles();
        if (!allLoadedFiles.isEmpty()) {
          LinkedHashSet<FileInfo> fileInfos=new LinkedHashSet<FileInfo>();
          Collection<FileSource> errorFiles=new LinkedHashSet<FileSource>();
          for (          FileResult fileResult : allLoadedFiles) {
            FileSource fileSource=fileResult.getFileSource();
            if (fileResult.isSuccess()) {
              String filePath=fileSource.getFileSrc();
              fileInfos.add(new FileInfo(fileSource.getBasePath(),fileSource.getTimestamp(),false,false,null));
            }
 else {
              errorFiles.add(fileSource);
            }
          }
          browser.addFiles(fileInfos);
          if (errorFiles.size() > 0) {
            browser.removeFiles(errorFiles);
          }
        }
      }
      boolean isLast=done != null;
      browser.addResponse(response,isLast);
      if (!isLast) {
        writer.print(NOOP);
        writer.flush();
        return;
      }
    }
    Command command=null;
    if (start != null) {
      browser.resetFileSet();
      urlTranslator.clear();
      forwardingMapper.clear();
      Command commandRunning=browser.getCommandRunning();
      if (commandRunning != null) {
        JsonCommand jsonCommand=gson.fromJson(commandRunning.getCommand(),JsonCommand.class);
        if (jsonCommand.getCommand().equals(JsonCommand.CommandType.RESET.getCommand())) {
          command=browser.getLastDequeuedCommand();
        }
      }
    }
 else {
      command=browser.dequeueCommand();
    }
    writer.print(command != null ? command.getCommand() : NOOP);
  }
  writer.flush();
}