private async Task <List <BuilderParticipant> > AddFunctionalRoleParticipantsAsync(
            Invitation invitation,
            List <BuilderParticipant> meetingParticipants,
            List <ParticipantsForCommand> functionalRoleParticipants)
        {
            var codes           = functionalRoleParticipants.Select(p => p.InvitedFunctionalRole.Code).ToList();
            var functionalRoles =
                await _functionalRoleApiService.GetFunctionalRolesByCodeAsync(_plantProvider.Plant, codes);

            foreach (var participant in functionalRoleParticipants)
            {
                var fr = functionalRoles.SingleOrDefault(p => p.Code == participant.InvitedFunctionalRole.Code);
                if (fr != null)
                {
                    invitation.AddParticipant(new Participant(
                                                  _plantProvider.Plant,
                                                  participant.Organization,
                                                  IpoParticipantType.FunctionalRole,
                                                  fr.Code,
                                                  null,
                                                  null,
                                                  null,
                                                  fr.Email,
                                                  null,
                                                  participant.SortKey));
                    if (fr.UsePersonalEmail != null && fr.UsePersonalEmail == false && fr.Email != null)
                    {
                        meetingParticipants.AddRange(InvitationHelper.SplitAndCreateOutlookParticipantsFromEmailList(fr.Email));
                    }
                    if (fr.InformationEmail != null)
                    {
                        meetingParticipants.AddRange(InvitationHelper.SplitAndCreateOutlookParticipantsFromEmailList(fr.InformationEmail));
                    }
                    foreach (var person in participant.InvitedFunctionalRole.InvitedPersons)
                    {
                        var frPerson = fr.Persons.SingleOrDefault(p => p.AzureOid == person.AzureOid.ToString());
                        if (frPerson != null)
                        {
                            invitation.AddParticipant(new Participant(
                                                          _plantProvider.Plant,
                                                          participant.Organization,
                                                          IpoParticipantType.Person,
                                                          fr.Code,
                                                          frPerson.FirstName,
                                                          frPerson.LastName,
                                                          frPerson.UserName,
                                                          frPerson.Email,
                                                          new Guid(frPerson.AzureOid),
                                                          participant.SortKey));
                            meetingParticipants = InvitationHelper.AddPersonToOutlookParticipantList(frPerson, meetingParticipants, person.Required);
                        }
                    }
                }
                else
                {
                    throw new IpoValidationException(
                              $"Could not find functional role with functional role code '{participant.InvitedFunctionalRole.Code}' on participant {participant.Organization}.");
                }
            }
            return(meetingParticipants);
        }