Remove a binary breaking change introduced in nhibernate#305

Author: hazzik

src/NHibernate/Mapping/ByCode/IPlainPropertyContainerMapper.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Linq.Expressions;
 using System.Reflection;
+using NHibernate.Mapping.ByCode.Impl.CustomizersImpl;
 
 namespace NHibernate.Mapping.ByCode
 {
@@ -41,7 +42,6 @@ public interface IBasePlainPropertyContainerMapper<TContainer> : IMinimalPlainPr
 		void Component<TComponent>(Expression<Func<TContainer, TComponent>> property, Action<IComponentMapper<TComponent>> mapping);
 		void Component<TComponent>(Expression<Func<TContainer, TComponent>> property);
 		void Component<TComponent>(Expression<Func<TContainer, IDictionary>> property, TComponent dynamicComponentTemplate, Action<IDynamicComponentMapper<TComponent>> mapping);
-		void Component<TComponent>(Expression<Func<TContainer, IDictionary<string, object>>> property, TComponent dynamicComponentTemplate, Action<IDynamicComponentMapper<TComponent>> mapping) where TComponent : class;
 
 		void Component<TComponent>(string notVisiblePropertyOrFieldName, Action<IComponentMapper<TComponent>> mapping);
 		void Component<TComponent>(string notVisiblePropertyOrFieldName);
@@ -56,4 +56,23 @@ public interface IPlainPropertyContainerMapper<TContainer> : IBasePlainPropertyC
 		void OneToOne<TProperty>(Expression<Func<TContainer, TProperty>> property, Action<IOneToOneMapper<TProperty>> mapping) where TProperty : class;
 		void OneToOne<TProperty>(string notVisiblePropertyOrFieldName, Action<IOneToOneMapper<TProperty>> mapping) where TProperty : class;
 	}
+	
+	public static class BasePlainPropertyContainerMapperExtensions
+	{
+		//6.0 TODO: Merge into IBasePlainPropertyContainerMapper<> interface
+		public static void Component<TContainer, TComponent>(
+			this IBasePlainPropertyContainerMapper<TContainer> mapper,
+			Expression<Func<TContainer, IDictionary<string, object>>> property,
+			TComponent dynamicComponentTemplate,
+			Action<IDynamicComponentMapper<TComponent>> mapping) where TComponent : class
+		{
+			if (!(mapper is PropertyContainerCustomizer<TContainer> customizer))
+			{
+				throw new NotSupportedException(
+					"IBasePlainPropertyContainerMapper<TContainer> should be a PropertyContainerCustomizer<TContainer>");
+			}
+
+			customizer.Component(property, dynamicComponentTemplate, mapping);
+		}
+	}
 }