public async Task DeleteIdentity(Guid id)
 {
     if (IdentitiesIdMap.TryGetValue(id, out Identity identity))
     {
         IdentitiesIdMap.Remove(id);
         IdentitiesIdentifierMap.Remove(identity.Identifier);
     }
 }
 public async Task <Identity> GetIdentity(Guid id)
 {
     if (IdentitiesIdMap.TryGetValue(id, out Identity identity))
     {
         return(identity);
     }
     return(null);
 }