/// <summary>
/// Checks if the voter already voted in the campaign
/// </summary>
/// <param name="campaignId"></param>
/// <param name="voterIdentity"></param>
/// <returns>bool</returns>∂
private async Task <bool> HasAlreadyVoted(ObjectId campaignId, String voterIdentity)
{
return(await voteRepository.HasAlreadyVoted(campaignId, voterIdentity));
}