Converter declared on Node.lazyLoadingContext so that Spring Data Neo4j does not classify that property as an association.
Spring Data Neo4j decides "association or property" purely by whether the driver can write the type, and AbstractMappingContext resolves an association's target type before it honours @Transient. Without this, LazyLoadingContext - and transitively the whole internal Graphglue object graph - would be mapped as entities and the mapping context would fail to build.
It is never invoked, because the property it is declared on is transient.