Investigate support for complex key types

[meistermeier]

Given our PersonWithCustomId from the test suite:

When altering the PersonId to something like:

@Value
public static class PersonId {
	private final Long id;
	private final String ding;
}

it is not possible to simple query/delete.. byId
This is due to the fact that the converter needs to be not only a GenericConverter but also a Neo4jPersistentPropertyToMapConverter to reflect the composite nature of the property.

The question originally appeared over at https://stackoverflow.com/questions/69976873/how-can-i-query-multiple-nodes-with-complex-key-usind-spring-data-neo4j

[meistermeier]

Solved with #2618