This release includes a big amount of bugfixes. Specifically, following issues were fixed: * Embeddable classes are now allowed in inheritance trees [4097](https://github.com/doctrine/doctrine2/issues/4097) * Removed some object hash collisions caused by entity merging [1465](https://github.com/doctrine/doctrine2/pull/1465) * Allowed usage of mathematical operators in DQL `HAVING` clauses [5598](https://github.com/doctrine/doctrine2/pull/5598) * Fixed cloning of proxies with private properties at multiple inheritance levels [5755](https://github.com/doctrine/doctrine2/pull/5755) * Entity insertions are correctly cleared when a specific entity is to be cleared [5849](https://github.com/doctrine/doctrine2/issues/5849) * Corrected hydration of fetch-joins that use composite keys [5762](https://github.com/doctrine/doctrine2/issues/5762) * Metadata exporters now only export the owning side metadata in a one-to-one relation [5858](https://github.com/doctrine/doctrine2/issues/5858) * Corrected hydration of JTI entities when `NULL` is retrieved for a `simple_array` or `json_array` field [5989](https://github.com/doctrine/doctrine2/issues/5989) * Correctly expire L2 cache query caches, based on entity region cache timestamp [6001](https://github.com/doctrine/doctrine2/issues/6001) Total issues resolved: **18** - [1465: spl_object_hash conflict on Merge](https://github.com/doctrine/doctrine2/pull/1465) - [4097: DDC-3303: @ORM\Embedded does not work with extending classes](https://github.com/doctrine/doctrine2/issues/4097) - [4277: DDC-3467: Embeddable in inheritance must currently be protected](https://github.com/doctrine/doctrine2/issues/4277) - [5598: HAVING clause with variable and *, / math operators](https://github.com/doctrine/doctrine2/pull/5598) - [5599: Fix #5598 issue with /, * in DQL not translating query components properly](https://github.com/doctrine/doctrine2/pull/5599) - [5689: Avoid conflicts due to spl_object_hash](https://github.com/doctrine/doctrine2/pull/5689) - [5755: Error on entity clone for MappedSuperclass fields](https://github.com/doctrine/doctrine2/issues/5755) - [5762: fetch join using composite key on join entity fails to hydrate correctly](https://github.com/doctrine/doctrine2/issues/5762) - [5768: Fixes #5755 - Parent class fields are not cloned](https://github.com/doctrine/doctrine2/pull/5768) - [5776: add functional test and bug fix for issue #5762](https://github.com/doctrine/doctrine2/pull/5776) - [5849: `UnitOfWork#clear()` doesn't clear `entityInsertions` when `entityName` is passed](https://github.com/doctrine/doctrine2/issues/5849) - [5850: Clear `UnitOfWork#$entityInsertions` for specific entityName](https://github.com/doctrine/doctrine2/pull/5850) - [5858: Exporters should only inspect `joinColumns` for owning side in bi-directional OneToOne](https://github.com/doctrine/doctrine2/pull/5858) - [5867: Allow the usage of embedded objects on parent classes](https://github.com/doctrine/doctrine2/pull/5867) - [5975: Fix hydration after fetch join on entity with composite primary key](https://github.com/doctrine/doctrine2/pull/5975) - [5989: `SimpleObjectHydrator` produces wrong values with inheritance table and simple array type](https://github.com/doctrine/doctrine2/issues/5989) - [6001: Make second level cache query cache rely on entity region timestamp](https://github.com/doctrine/doctrine2/pull/6001) - [6004: Fix hydration in a joined inheritance with simple array or json array](https://github.com/doctrine/doctrine2/pull/6004)