Program: 7102
Project: 7102
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<FileSource> successFiles=loadedFiles.getSuccessFiles();
        LinkedHashSet<FileInfo> fileInfos=new LinkedHashSet<FileInfo>();
        for (        FileSource f : successFiles) {
          fileInfos.add(new FileInfo(f.getFileSrc().substring(6),f.getTimestamp(),false));
        }
        browser.addFiles(fileInfos);
        Collection<String> errorFiles=loadedFiles.getErrorFiles();
        if (errorFiles.size() > 0) {
          browser.removeFiles(errorFiles);
        }
 else         if (loadedFiles.getMessage().equals("String_Node_Str")) {
          browser.resetFileSet();
        }
      }
      boolean isLast=done != null;
      browser.addResponse(response,isLast);
      if (!isLast) {
        writer.print(NOOP);
        writer.flush();
        return;
      }
    }
    Command command=null;
    if (start != null) {
      browser.resetFileSet();
      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<FileSource> successFiles=loadedFiles.getSuccessFiles();
        LinkedHashSet<FileInfo> fileInfos=new LinkedHashSet<FileInfo>();
        for (        FileSource f : successFiles) {
          fileInfos.add(new FileInfo(f.getFileSrc().substring(6),f.getTimestamp(),false,false));
        }
        browser.addFiles(fileInfos);
        Collection<String> errorFiles=loadedFiles.getErrorFiles();
        if (errorFiles.size() > 0) {
          browser.removeFiles(errorFiles);
        }
 else         if (loadedFiles.getMessage().equals("String_Node_Str")) {
          browser.resetFileSet();
        }
      }
      boolean isLast=done != null;
      browser.addResponse(response,isLast);
      if (!isLast) {
        writer.print(NOOP);
        writer.flush();
        return;
      }
    }
    Command command=null;
    if (start != null) {
      browser.resetFileSet();
      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();
}