How do I use *attributeless* MEF 2.0 to export methods that match a specific signature? - plugins

Question

I'm interested in using external assemblies as plugins. Instead of basing import/export on interfaces, I want to be able to export methods from random assemblies in cases where the method meets a certain signature and import them as method proxies. I have done this previously via custom reflection code but I would rather use Microsoft's built in functionality. Unfortunately, the documentation for MEF v2 is quite lacking.
So how can I change this to successfully create method proxies:
[Test()]
public void ProxyTest()
{
var builder = new ConventionBuilder();
var filter = new MemberFilter((info, obj) => info.DeclaringType != typeof(object) && info.MemberType == MemberTypes.Method && ((MethodInfo)info).IsBoolTask());
builder.ForTypesMatching((classType) => classType.FindMembers(MemberTypes.Method, ReflectionExtensions.Everything, filter, null).Any()).Export<Func<Task<bool>>>();
var host = new ContainerConfiguration().WithAssembly(this.GetType().Assembly, builder).CreateContainer();
var container = new ProxyContainer();
host.SatisfyImports(container);
}
public class ProxyContainer
{
[ImportMany]
public IEnumerable<Lazy<Func<Task<bool>>>> LazyProxyMethod
{
get;
set;
}
[ImportMany]
public IEnumerable<Func<Task<bool>>> ProxyMethods
{
get;
set;
}
}
public static class StaticThing
{
public static Task<bool> MyStaticMethod() =>
Task.FromResult(true);
}
public class InstanceThing
{
public Task<bool> MyInstanceMethod() =>
Task.FromResult(true);
}
public class InstanceWithStaticThing
{
public static Task<bool> MyStaticMethod() =>
Task.FromResult(true);
}
public static class ReflectionExtensions
{
public const BindingFlags Everything = BindingFlags.Instance | BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static | BindingFlags.FlattenHierarchy;
public static bool IsBoolTask(this MethodInfo method) =>
null != method &&
typeof(Task<bool>) == method.ReturnType;
}