public Task<List<GoogleDriveFileHolder>> queryFiles(@Nullable final String folderId) {
        return Tasks.call(mExecutor, new Callable<List<GoogleDriveFileHolder>>() {
                    @Override
                    public List<GoogleDriveFileHolder> call() throws Exception {
                        List<GoogleDriveFileHolder> googleDriveFileHolderList = new ArrayList<>();
                        String parent = "root";
                        if (folderId != null) {
                            parent = folderId;
                        }

                        FileList result = mDriveService.files().list().setQ("'" + parent + "' in parents").setFields("files(id, name,size,createdTime,modifiedTime,starred)").setSpaces("drive").execute();

                        for (int i = 0; i < result.getFiles().size(); i++) {

                            GoogleDriveFileHolder googleDriveFileHolder = new GoogleDriveFileHolder();
                            googleDriveFileHolder.setId(result.getFiles().get(i).getId());
                            googleDriveFileHolder.setName(result.getFiles().get(i).getName());
                            if (result.getFiles().get(i).getSize() != null) {
                                googleDriveFileHolder.setSize(result.getFiles().get(i).getSize());
                            }

                            if (result.getFiles().get(i).getModifiedTime() != null) {
                                googleDriveFileHolder.setModifiedTime(result.getFiles().get(i).getModifiedTime());
                            }

                            if (result.getFiles().get(i).getCreatedTime() != null) {
                                googleDriveFileHolder.setCreatedTime(result.getFiles().get(i).getCreatedTime());
                            }

                            if (result.getFiles().get(i).getStarred() != null) {
                                googleDriveFileHolder.setStarred(result.getFiles().get(i).getStarred());
                            }

                            googleDriveFileHolderList.add(googleDriveFileHolder);

                        }


                        return googleDriveFileHolderList;


                    }
                }
        );
    }