code: public MucConfigFormManager setRoomSecret(String secret)
                      throws MucConfigurationNotSupportedException {
          if (!answerForm.hasField(MUC_ROOMCONFIG_ROOMSECRET)) {
              throw new MucConfigurationNotSupportedException(MUC_ROOMCONFIG_ROOMSECRET);
          }
          answerForm.setAnswer(MUC_ROOMCONFIG_ROOMSECRET, secret);
          return this;
      }
docs: Set the room secret, aka the room password. If set and enabled, the password is required to
  join the room. Note that this does only set it by does not enable password protection. Use
  {@link #setAndEnablePassword(String)} to set a password and make the room protected.
  
  @param secret the secret/password.
  @return a reference to this object.
  @throws MucConfigurationNotSupportedException