code: public FTPUploadRequest setUsernameAndPassword(String username, String password) {
          if (username == null || "".equals(username)) {
              throw new IllegalArgumentException("Specify FTP account username!");
          }
  
          if (password == null || "".equals(password)) {
              throw new IllegalArgumentException("Specify FTP account password!");
          }
  
          ftpParams.username = username;
          ftpParams.password = password;
          return this;
      }
docs: Set the credentials used to login on the FTP Server.
  @param username account username
  @param password account password
  @return {@link FTPUploadRequest}