[master] Diagnostic new feature - corrupted cache

[rfelcman]

This is new diagnostic feature which could help developers to analyze inconsistent query results. Inconsistent means, that there is mix of managed and detached entities in the query result by logical error in their code. It should happens if JPA L2 caching is enabled.
E.g. let's have following code:

em.remove(branchBDiagnostic);
commitTransaction(em);
//branchBDiagnostic is in Detached state
...
em.getTransaction().begin();
branchADiagnostic.getBranchBs().add(branchBDiagnostic);
branchBDiagnostic.setBranchA(branchADiagnostic);
//Detached entity (branchBDiagnostic) is not persisted again - logical error
commitTransaction(em);

//This em.find() will resolve objects from cache
BranchADiagnostic branchADiagnosticFindResult = em.find(BranchADiagnostic.class, BRANCHA_ID);
...

if cache validation is enabled by
persistence unit property
<property name="eclipselink.query-results-cache.validation" value="true"/>
or by query hint
query.setHint("eclipselink.query-results-cache.validation", true);
EclipseLink will print into log output messages like

[EL Warning]: cache: 2022-12-07 14:26:50.86--UnitOfWork(1211586911)--stack of visited objects that refer to the corrupt object: [BranchADiagnostic{id=1}]
[EL Warning]: cache: 2022-12-07 14:26:50.86--UnitOfWork(1211586911)--corrupt object referenced through mapping: org.eclipse.persistence.mappings.OneToManyMapping[branchBs]
[EL Warning]: cache: 2022-12-07 14:26:50.86--UnitOfWork(1211586911)--corrupt object: BranchBDiagnostic{id=11}

Note: <Entity>.toString() method is used.

Signed-off-by: Radek Felcman [email protected]

[lukasj]

LGTM