public class CheckIfOwnedByPool : BasePlugin
{
    public CheckIfOwnedByPool(string unsecure, string secure)
        : base(unsecure, secure)
    {

    }


    public override void ExecutePluginLogic(XrmObjects xrmObjects)
    {

        if (xrmObjects.PluginContext.MessageName.ToLower() == "update" && xrmObjects.PluginContext.PreEntityImages.Contains("entity"))
        {

            Guid PoolId = Guid.Empty;
            List<Guid> allowedRoles = new List<Guid>();
            var entity = xrmObjects.PluginContext.PreEntityImages["entity"];

            //retrieve id of "POOL" team and allowed roles GUIDs from plugin step XML config. GUID varies from environment to environment...
            try
            {
                PoolId = new Guid(GetAllNodes("ownerconfig")[0].Attributes["value"].InnerText);
                GetAllNodes("roles")[0].Attributes["value"].InnerText.Split(';').ToList().ForEach(x => allowedRoles.Add(new Guid(x)));
            }
            catch (Exception ex)
            {
                throw new InvalidPluginExecutionException(string.Format("Error deserializing plugin step XML config: {0}", ex.Message));
            }

            if (PoolId == Guid.Empty || allowedRoles.Count == 0)
                return;

            //if entity is owned by team called "POOL"
            if (((EntityReference)entity["ownerid"]).Id == PoolId)
            {
                using (XrmServiceContext ctx = new XrmServiceContext(xrmObjects.Service))
                {
                    //retrieve current user roles
                    var userRoles = ctx.SystemUserRolesSet.Where(x => x.SystemUserId == xrmObjects.PluginContext.InitiatingUserId).ToList();

                    //check if current user has one of required roles
                    if (!userRoles.Any(x => allowedRoles.Any(y => y == x.RoleId.Value)))
                        throw new InvalidPluginExecutionException("You do not have access to modify this record. Please see with your supervisor");

                }

            }

        }
    }
}