code: public ApiResponse<Void> postFleetsFleetIdMembersWithHttpInfo(Long fleetId, String datasource, String token,
              FleetInvitation fleetInvitation) throws ApiException {
          com.squareup.okhttp.Call call = postFleetsFleetIdMembersValidateBeforeCall(fleetId, datasource, token,
                  fleetInvitation, null);
          return apiClient.execute(call);
      }
docs: Create fleet invitation Invite a character into the fleet. If a character
  has a CSPA charge set it is not possible to invite them to the fleet
  using ESI --- SSO Scope: esi-fleets.write_fleet.v1
  
  @param fleetId
  ID for a fleet (required)
  @param datasource
  The server name you would like data from (optional, default to
  tranquility)
  @param token
  Access token to use if unable to set a header (optional)
  @param fleetInvitation
  (optional)
  @return ApiResponse&lt;Void&gt;
  @throws ApiException
  If fail to call the API, e.g. server error or cannot
  deserialize the response body