IEnumerable <Type> GetConnectableTypes()
{
var connectableTypes = new HashSet <Type>();
connectableTypes.UnionWith(nodeViews.Values.SelectMany(x => x.ConnectionTypes));
connectableTypes.UnionWith(GetSerializedScriptableObjectFields().Select(x => x.FieldType));
var derivedTypes = new HashSet <Type>();
derivedTypes.UnionWith(connectableTypes.SelectMany(x => NodeEditorUtilities.GetDerivedTypes(x, false, false)));
connectableTypes.UnionWith(derivedTypes);
return(connectableTypes);
}