Fix FieldDescription for multi-level embedded properties

[ghost]

I am targeting this branch, because it's BC bug fix..

Closes #826

Changelog

### Fixed
- Fix FieldDescription for multi-level embedded properties

To do

• Update the tests

[kunicmarko20]

Can you add a test for this, please?

[ghost]

Tests updated

[kunicmarko20]

Please configure your IDE to always add a newline at end of file, this will make the red pictogram disappear.

[ghost]

Should be OK

[kunicmarko20]

Can you break this one more time? We follow PSR-2 and your line shouldn't be longer than 120 chars

[ghost]

Done

[greg0ire]

From the docs:

Embeddables can only contain properties with basic @column mapping.

I'm not sure whether we should support this.

[greg0ire]

Please find an official source showing that multi-level embeddables are supported by Doctrine.

[bonfante]

@greg0ire
when looking to doctrine repo I can't find any doc supporting nested embeddables, but in there is a lot of PR to this behevour doctrine/orm/pull/1309, and it just works.
Just use only embeddables
I get similir issue with nested embeddables in the list. Would be greate to add this functionality.
But maybe is a good idea to change ModelManager::getMetadata too.
It was the first solution I found, but it still has issues with ['editable' => true] in configureListFields.

    /**
     * @param string $class
     *
     * @return ClassMetadata
     * @throws \RuntimeException
     * @throws \ReflectionException
     * @throws \Doctrine\Common\Persistence\Mapping\MappingException
     */
    public function getMetadata($class)
    {
        try {
            return $this->getEntityManager($class)->getMetadataFactory()->getMetadataFor($class);
        } catch (\RuntimeException $exception) {
            $metadata = $this->registry->getEntityManager()->getMetadataFactory()->getMetadataFor($class);
            if ($metadata->isEmbeddedClass) {
                return $metadata;
            }
            throw new \RuntimeException(sprintf('Failed to get metadata for class %s', $class),$exception);;
        }
    }

[greg0ire]

Looking at doctrine/orm#1311, it seems indeed to be somewhat supported

[OskarStark]

Nice simplicifaction 👍