bool IReadOnlyDictionary <MemberInfo, MemberMetadata> .TryGetValue(MemberInfo key, out MemberMetadata value)
 {
     return(_metadata.TryGetValue(key, out value));
 }
 IImmutableDictionary <MemberInfo, MemberMetadata> IImmutableDictionary <MemberInfo, MemberMetadata> .SetItem(MemberInfo key, MemberMetadata value)
 {
     return(_metadata.SetItem(key, value));
 }