Neos\Flow\Property\TypeConverter\PersistentObjectConverter::findObjectByIdentityProperties PHP Method

    protected function findObjectByIdentityProperties(array $identityProperties, $type)
    {
        $query = $this->persistenceManager->createQueryForType($type);
        $classSchema = $this->reflectionService->getClassSchema($type);
        $equals = [];
        foreach ($classSchema->getIdentityProperties() as $propertyName => $propertyType) {
            if (isset($identityProperties[$propertyName])) {
                if ($propertyType === 'string') {
                    $equals[] = $query->equals($propertyName, $identityProperties[$propertyName], false);
                } else {
                    $equals[] = $query->equals($propertyName, $identityProperties[$propertyName]);
                }
            }
        }
        if (count($equals) === 1) {
            $constraint = current($equals);
        } else {
            $constraint = $query->logicalAnd(current($equals), next($equals));
            while (($equal = next($equals)) !== false) {
                $constraint = $query->logicalAnd($constraint, $equal);
            }
        }
        $objects = $query->matching($constraint)->execute();
        $numberOfResults = $objects->count();
        if ($numberOfResults === 1) {
            return $objects->getFirst();
        } elseif ($numberOfResults === 0) {
            return null;
        } else {
            throw new DuplicateObjectException('More than one object was returned for the given identity, this is a constraint violation.', 1259612399);
        }
    }