Fix TypeLoadException in StaticProxyFactory when class has not visible interfaces

Fixes #1643

Author: hazzik

src/NHibernate.Test/StaticProxyTest/StaticProxyFactoryFixture.cs

@@ -0,0 +1,28 @@
+using System.Collections.Generic;
+using NHibernate.Proxy;
+using NUnit.Framework;
+
+namespace NHibernate.Test.StaticProxyTest
+{
+	public class StaticProxyFactoryFixture
+	{
+		internal interface ISomething
+		{
+			int Id { get; }
+		}
+
+		public class TestClass : ISomething
+		{
+			public virtual int Id { get; set; }
+		}
+
+		[Test]
+		public void CanCreateProxyForClassWithInternalInterface()
+		{
+			var factory = new StaticProxyFactory();
+			factory.PostInstantiate(typeof(TestClass).FullName, typeof(TestClass), new HashSet<System.Type> {typeof(INHibernateProxy)}, null, null, null);
+			var proxy = factory.GetProxy(1, null);
+			Assert.That(proxy, Is.Not.Null);
+		}
+	}
+}

src/NHibernate/Proxy/NHibernateProxyBuilder.cs

@@ -74,6 +74,8 @@ public TypeInfo CreateProxyType(System.Type baseType, IReadOnlyCollection<System
 				interfaces.Add(baseType);
 			}
 
+			interfaces.RemoveWhere(i => !i.IsVisible);
+
 			var typeBuilder = moduleBuilder.DefineType(typeName, typeAttributes, parentType, interfaces.ToArray());
 
 			var lazyInitializerField = typeBuilder.DefineField("__lazyInitializer", LazyInitializerType, FieldAttributes.Private);