Approval Engine that throws an exception if a user tries to approve their own content

ValidatingApprovalEngine.cs

using EPiServer.Approvals;
using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using EPiServer.Framework;
using EPiServer.ServiceLocation;
using EPiServer.Framework.Initialization;
using EPiServer.Security;

namespace ApprovalSequences
{
    [ModuleDependency(typeof(EPiServer.Web.InitializationModule))]
    public class ApprovalEngineInterceptor : IConfigurableModule
    {
        public void ConfigureContainer(ServiceConfigurationContext context)
        {
            context.Services.Intercept<IApprovalEngine>(
                (locator, defaultEngine) => new ValidatingApprovalEngine(defaultEngine));
        }

        public void Initialize(InitializationEngine context) { }
        public void Uninitialize(InitializationEngine context) { }
    }

    public class ValidatingApprovalEngine : IApprovalEngine
    {
        private readonly IApprovalEngine _defaultApprovalEngine;
        public ValidatingApprovalEngine(IApprovalEngine defaultApprovalEngine)
        {
            _defaultApprovalEngine = defaultApprovalEngine;
        }

        public Task ApproveAsync(int id, string username, int stepIndex, ApprovalDecisionScope scope, string comment)
        {
            if (username == PrincipalInfo.CurrentPrincipal.Identity.Name)
            {
                return Task.FromException(new Exception("You cannot approve your own content"));
            }
            else
            {
                return _defaultApprovalEngine.ApproveAsync(id, username, stepIndex, scope, comment);
            }
        }

        public Task AbortAsync(IEnumerable<int> ids, string username) => _defaultApprovalEngine.AbortAsync(ids, username);

        public Task RejectAsync(int id, string username, int stepIndex, ApprovalDecisionScope scope, string comment) => _defaultApprovalEngine.RejectAsync(id, username, stepIndex, scope, comment);

        public Task<IEnumerable<Approval>> StartAsync(IEnumerable<Uri> references, string username, bool throwOnMissingDefinition) => _defaultApprovalEngine.StartAsync(references, username, throwOnMissingDefinition);
    }
}