Assembly: System.Xaml (in System.Xaml.dll)
The default implementation returns the underlying member information, which is based on construction. If the MemberInfo object is constructed with a signature that does not provide enough information to set the underlying member, this method returns null.
If an underlying member was set during construction, you should not need to call this method.
This method is invoked when a caller gets a value from UnderlyingMember. Override this method if you want to report uniform results for an entire XamlMember derived class, or if you have specialized metadata available to determine this on a per-case basis. Make sure to implement LookupUnderlyingGetter, LookupUnderlyingSetter, and so that they all return correlated results.