code: public FTPUploadRequest addFileToUpload(String filePath) throws FileNotFoundException {
          UploadFile file = new UploadFile(filePath);
  
          file.setProperty(FTPUploadTask.PARAM_REMOTE_PATH, new File(filePath).getName());
  
          params.files.add(file);
          return this;
      }
docs: Add a file to be uploaded in the default working directory of the account used to login
  into the FTP server. The uploaded file name will be the same as the local file name, so
  if you are uploading {@code /path/to/myfile.txt}, you will have {@code myfile.txt}
  inside the default remote working directory.
  If any of the directories of the specified remote path does not exist,
  they will be automatically created. You can also set with which permissions to create them
  by using {@link FTPUploadRequest#setCreatedDirectoriesPermissions(UnixPermissions)}
  method.
  @param filePath path to the local file on the device
  @return {@link FTPUploadRequest}
  @throws FileNotFoundException if the local file does not exist