private ProjectionTargetContainer(IRootTargetContainer root, Type sourceElementType, Type outputElementType)
{
Root = root;
SourceElementType = sourceElementType;
OutputElementType = outputElementType;
SourceEnumerableType = typeof(IEnumerable <>).MakeGenericType(sourceElementType);
OutputEnumerableType = typeof(IEnumerable <>).MakeGenericType(outputElementType);
Root.AddKnownType(OutputEnumerableType);
}