I've registered an instance of the `IMemoryCache` (Microsoft.Extensions.Cachine.Memory 3.1.5) as a singleton with a `SimpleContainer` for use with Caliburn Micro for a WPF application that I'm writing in .Net Core 3.1.
In my Bootstrapper, I have the following code

```
public class Bootstrapper : BootstrapperBase
{
    private SimpleContainer _container = new SimpleContainer();

    public Bootstrapper()
    {
        Initialize();
    }

    protected override void Configure()
    {
        _container.Instance(_container);

        _container
            .Singleton<IWindowManager, WindowManager>()
            .Singleton<IEventAggregator, EventAggregator>()
            .Singleton<IMemoryCache, MemoryCache>();
     }

```

When I come to use the `IMemoryCache` in a class it throws an Exception as it requires `MemoryCacheOptions` to be passed into the constructor of the MemoryCache.

I've tried to add MemoryCacheOptions to the Singleton registration but that's not accepted.

This is the constructor of my `ReferenceDataHelper` class where I'm trying to inject the IMemoryCache, it fails with a `System.Reflection.TargetInvocationException` when it constructs the ReferenceDataHelper class.

```
    public class ReferenceDataHelper : IReferenceDataHelper
{
    private IMemoryCache _memoryCache;
    private IReferenceDataHandler _referenceDataHandler;

    public ReferenceDataHelper(IReferenceDataHandler referenceDataHandler, IMemoryCache memoryCache)
    {
        _referenceDataHandler = referenceDataHandler; 
        _memoryCache = memoryCache;
    }

```

I can't figure out how to set this up - can anyone offer some help?
Thanks!