public EdgeConverter(Type type, KeyConverter keyConverter)
     : base(type, keyConverter, KeyForType.Edge)
 {
     sourceIdGetter = type.GetNodeIdGetter <SourceAttribute>();
     targetIdGetter = type.GetNodeIdGetter <TargetAttribute>();
 }
 private static Func <Type, ContentConverter <NodeType> > GetNodeConverterGetter(KeyConverter keyConverter)
 {
     return((propertyType) => new NodeConverter(
                type: propertyType,
                keyConverter: keyConverter));
 }