final Property property = context.find( Property.class );
if( property != null && property.definition() instanceof ListProperty &&
property.service( PossibleTypesService.class ).types().size() == 1 )
{
final ElementType memberType = property.definition().getType();
final SortedSet<PropertyDef> properties = memberType.properties();
if( properties.size() == 1 )
{
final PropertyDef memberProperty = properties.first();