ClassNotFoundException with APOC when running with embedded Java API and custom procedure classloader

[DirkMahler]

jQAssistant uses the Java API of Neo4j 4.4.x in embedded mode and allows registration of custom procedures (e.g. APOC), internally mapped to:

GlobalProcedures.registerProcedure(procedureType);

The procedureType is loaded using a custom classloader having the classloader which provides the Neo4j classes as parent. The registration itself is successful, but trying to use the procedure

call apoc.help('help')

fails with

Neo.ClientError.Procedure.ProcedureCallFailed
Failed to invoke procedure `apoc.help`: Caused by: java.lang.NoClassDefFoundError: apoc/help/Help

The issue seems to be related to the hard-coded classloader used in https://github.com/neo4j/neo4j/blob/4.4/community/procedure/src/main/java/org/neo4j/procedure/impl/ProcedureCompilation.java#L840, I replaced it locally with the TCCL and everything is fine. If required I can provide a PR, but we'd need to align how to create a test for it (doesn't seem trivial).
Let me know if I should provide a demonstrator project with instructions on how to reproduce.

Neo4j Version: 4.4.26
Operation System: Win10 (probably any)
API: Embedded Java API/ Cypher

[hedengran]

Hi @DirkMahler, thank you for the report. We are looking into it, and will get back to you.