Dynamics365 - Check if a user exists in a team

UserExistsInTeam.cs

using System.Activities;
using System.Linq;
using Microsoft.Xrm.Sdk;
using Microsoft.Xrm.Sdk.Workflow;

namespace GeneralTools
{
    public class UserExistsInTeam : CodeActivity
    {
    
        public IWorkflowContext context;
        public IOrganizationServiceFactory serviceFactory;
        public IOrganizationService service;
        
        protected override void Execute(CodeActivityContext executionContext)
        {
            context = executionContext.GetExtension<IWorkflowContext>();
            serviceFactory = executionContext.GetExtension<IOrganizationServiceFactory>();
            service = serviceFactory.CreateOrganizationService(context.UserId);

            var userEr = UserArgument.Get<EntityReference>(executionContext);
            var teamEr = TeamArg.Get<EntityReference>(executionContext);

            var teamUsers = GetTeamMembers(teamEr.Id, service);
            var existence = teamUsers?.Entities?.ToList().Any(user => userEr.Id.Equals(user.Id)) ?? false;

            ExistenceArg.Set(executionContext, existence);

        }
        
        private static EntityCollection GetTeamMembers(Guid teamGuid, IOrganizationService service)
        {

            var userQuery = new QueryExpression("systemuser");
            userQuery.ColumnSet = new ColumnSet(true);
            var teamLink = new LinkEntity("systemuser", "teammembership", "systemuserid", "systemuserid", JoinOperator.Inner);
            var teamCondition = new ConditionExpression("teamid", ConditionOperator.Equal, teamGuid);
            teamLink.LinkCriteria.AddCondition(teamCondition);
            userQuery.LinkEntities.Add(teamLink);
            var retrievedUsers = service.RetrieveMultiple(userQuery);
            return retrievedUsers;
        }

        [Input("User")]
        [ReferenceTarget("systemuser")]
        [RequiredArgument]
        public InArgument<EntityReference> UserArgument { get; set; }

        [Input("Team")]
        [ReferenceTarget("team")]
        [RequiredArgument]
        public InArgument<EntityReference> TeamArg { get; set; }
        
        [Output("Exists")]
        public OutArgument<bool> ExistenceArg { get; set; }
    }
}