Neo4j silently drops null-valued properties — 'k' IN keys(n) is false after CREATE (n {k: null})

An integration test created a node with a property set to null — CREATE (n {orgId: $orgId}) where $orgId resolved to null — then asserted the property KEY was persisted with RETURN 'orgId' IN keys(n) AS has and expect(has).toBe(true). The assertion failed (got false) even though the CREATE ran and the node exists. The test was trying to prove the write path persists the field end-to-end, distinguishing "written as null" from "dropped".