First one is an exemple to default find record method, seccond is an exemple for custom find record

WidgetSliderNavContentResolve1r.php

<?php

  
    public function getWidgetBusinessEntityContent(Widget $widget)
    {
        $parameters = parent::getWidgetBusinessEntityContent($widget);

        /** @var WidgetSliderNav $widget */
        //get previous and next record if entity is set
        if ($entity = $widget->getEntity()) {
            $template = $widget->getTargetPattern();
            $repository = $this->entityManager->getRepository(get_class($entity));
            $entitiesAllowed = [];
            if(!$template)
            {
                $template = $this->businessPageHelper->guessBestPatternIdForEntity(new \ReflectionClass($entity), $entity->getId(), $this->entityManager);

            }
            if($template)
            {
                $entitiesAllowed = $this->businessPageHelper->getEntitiesAllowed($template, $this->entityManager);
            }
            try {
                $previousRecord = self::getPreviousRecord($repository, $entity, $entitiesAllowed);
                $parameters['previousRecord'] = $previousRecord;
            } catch (\Exception $e) {
                $parameters['previousRecord'] = null;
            }

            try {
                $nextRecord = self::getNextRecord($repository, $entity, $entitiesAllowed);
                $parameters['nextRecord'] = $nextRecord;
            } catch (\Exception $e) {
                $parameters['nextRecord'] = null;
            }
        }

        return $parameters;
    }

    protected static function getPreviousRecord($repository, $entity, $entitiesAllowed = [])
    {
            //run default method to get previous record
        if(!count($entitiesAllowed))
        {
            return null;
        }
        $queryBuilder = $repository->createQueryBuilder('a');
        $previousRecord = $queryBuilder
            ->where($queryBuilder->expr()->lt('a.id', ':id'))
            ->andWhere($queryBuilder->expr()->in('a', ':entitiesAllowed'))
            ->setParameters([
                'id'=> $entity->getId(),
                'entitiesAllowed' =>$entitiesAllowed
            ])
            ->orderBy('a.id', 'DESC')
            ->setMaxResults(1)
            ->getQuery()
            ->getOneOrNullResult();
        //if there isn't any previous record, we try to get the very last result
        if (!$previousRecord) {
            //run default method to get the very last record
            $queryBuilder = $repository->createQueryBuilder('a');
            $previousRecord = $queryBuilder
                ->where($queryBuilder->expr()->in('a', ':entitiesAllowed'))
                ->orderBy('a.id', 'DESC')
                ->setParameter('entitiesAllowed', $entitiesAllowed)
                ->setMaxResults(1)
                ->getQuery()
                ->getOneOrNullResult();
            //if the last record is the same as the entity, we set null
            if ($previousRecord === $entity) {
                $previousRecord = null;
            }
        }

        return $previousRecord;
    }

    /**
     * @param \Doctrine\ORM\EntityRepository $repository
     * @param mixed $entity
     * @param array $entitiesAllowed
     * @return mixed|null
     * @throws \Doctrine\ORM\NonUniqueResultException
     */
    protected static function getNextRecord($repository, $entity, $entitiesAllowed = [])
    {
        //check if an overriden method exists
        //run default method to get next record
        if(!count($entitiesAllowed))
        {
            return null;
        }
        $queryBuilder = $repository->createQueryBuilder('a');
        $nextRecord = $queryBuilder
            ->where($queryBuilder->expr()->gt('a.id', ':id'))
            ->andWhere($queryBuilder->expr()->in('a', ':entitiesAllowed'))
            ->setParameters([
                'id'=> $entity->getId(),
                'entitiesAllowed' =>$entitiesAllowed
            ])
            ->orderBy('a.id', 'ASC')
            ->setMaxResults(1)
            ->getQuery()
            ->getOneOrNullResult();
        //if there isn't any next record, we try to get the very first result
        if (!$nextRecord) {
            //run default method to get the very first record
            $queryBuilder = $repository->createQueryBuilder('a');
            $nextRecord = $queryBuilder
                ->where($queryBuilder->expr()->in('a', ':entitiesAllowed'))
                ->orderBy('a.id', 'ASC')
                ->setParameter('entitiesAllowed', $entitiesAllowed)
                ->setMaxResults(1)
                ->getQuery()
                ->getOneOrNullResult();
            //if the first record is the same as the entity, we set null
            if ($nextRecord === $entity) {
                $nextRecord = null;
            }
        }

        return $nextRecord;
    }

WidgetSliderNavContentResolver2.php

<?php
protected static function getPreviousRecord($repository, $entity, $entitiesAllowed = [])
    {
        if (method_exists($repository, 'getPreviousRecord')) {
            $previousRecord = null;
            $current = $entity;
            while($previousRecord = null && $current)
            {
                 
                $previous = $repository->getPreviousRecord($current->getId());
                if(in_array($previous, $entitiesAllowed))
                {
                  $previousrecord = $previous;
                } else {
                  $current = $previous;
                }
            }
        } 
        return $previousRecord;
    }