Magento 2.3 How to convert JSON response array to array of same type object REST API

I created a custom api to get review and rating summary:

public function getRatingSummary($productId)
{
    $result =[];
    $product        = $this->_productRepository->getById($productId);

    $idArray        = [$productId];
    $reviewsCollection      = $this->_reviewCollectionFactory->create()
                                ->addFieldToFilter('entity_pk_value',array("in" => $idArray))
                                ->addStatusFilter(MagentoReviewModelReview::STATUS_APPROVED)
                                ->addRateVotes();

    $ratingSummary  = $reviewsCollection->getSelect();
    $starsData = array();

    foreach ($reviewsCollection->getItems() as $review) {

        foreach( $review->getRatingVotes() as $_vote ) {
            $rating     = [];
            $percent    = $_vote->getPercent();
            $star       = ($percent/20);
            $productId  = $_vote->getEntityPkValue();

            $countReview    = $this->_reviewFactoryCustom->create()->getTotalReviews($productId,false);
            $review_id      = $_vote->getReviewId();
            $rating_id      = $_vote->getRatingId();

            $rating['rating_id']    = $rating_id;
            $rating['review_id']    = $review_id;
            $rating['product_id']   = $productId;     
            $rating['percent']      = $percent;
            $rating['star']         = $star;
            $rating['nickname']     = $review->getNickname();                  
            $items[]                = $rating;
            $starData[$star][]      = $rating;
            $starsData[]            = $rating;
        }

    }

    if(count($items) > 0)   {           
        $results['all']     = $items;
        $result[1]['star']  = $starsData;            

        if(isset($starData[1]))
            $result[2]['count'][1] = count($starData[1]);
        else
            $result[2]['count'][1] = 0;

        if(isset($starData[2]))
            $result[2]['count'][2] = count($starData[2]);
        else
            $result[2]['count'][2] = 0;

        if(isset($starData[3]))
            $result[2]['count'][3] = count($starData[3]);
        else
            $result[2]['count'][3] = 0;

        if(isset($starData[4]))
            $result[2]['count'][4] = count($starData[4]);
        else
            $result[2]['count'][4] = 0;

        if(isset($starData[5]))
            $result[2]['count'][5] = count($starData[5]);
        else
            $result[2]['count'][5] = 0;

        $sum = $startSum = 0;

        foreach($result[2]['count'] as $number => $count) {
            $sum += $number * $count;
            $startSum +=  $count;   
        }

        $avg =  $sum/$startSum;

        $result [3]['rating']['all'] = count($results['all']);
        $result [3]['rating']['avg'] = round($avg,1);
    }

    return $result;
}

But the response I get is :

 [
{
    "star": [
        {
            "rating_id": "1",
            "review_id": "3",
            "product_id": "9",
            "percent": "100",
            "star": 5,
            "nickname": "XXXXX"
        },
        {
            "rating_id": "3",
            "review_id": "3",
            "product_id": "9",
            "percent": "60",
            "star": 3,
            "nickname": "XXXXX"
        },
        {
            "rating_id": "2",
            "review_id": "3",
            "product_id": "9",
            "percent": "100",
            "star": 5,
            "nickname": "XXXXX"
        },
        {
            "rating_id": "1",
            "review_id": "4",
            "product_id": "9",
            "percent": "40",
            "star": 2,
            "nickname": "YYYY"
        },
        {
            "rating_id": "3",
            "review_id": "4",
            "product_id": "9",
            "percent": "80",
            "star": 4,
            "nickname": "YYYY"
        },
        {
            "rating_id": "2",
            "review_id": "4",
            "product_id": "9",
            "percent": "80",
            "star": 4,
            "nickname": "YYYY"
        }
    ]
},
{
    "count": {
        "1": 0,
        "2": 1,
        "3": 1,
        "4": 2,
        "5": 2
    }
},
{
    "rating": {
        "all": 6,
        "avg": 3.8
    }
}
]

I want my response as an array of same type of object or something like this:

{
"star": [
    {
        "rating_id": "1",
        "review_id": "3",
        "product_id": "9",
        "percent": "100",
        "star": 5,
        "nickname": "XXXX"
    },
    {
        "rating_id": "3",
        "review_id": "3",
        "product_id": "9",
        "percent": "60",
        "star": 3,
        "nickname": "XXXX"
    },
    {
        "rating_id": "2",
        "review_id": "3",
        "product_id": "9",
        "percent": "100",
        "star": 5,
        "nickname": "XXXX"
    },
    {
        "rating_id": "1",
        "review_id": "4",
        "product_id": "9",
        "percent": "40",
        "star": 2,
        "nickname": "YYYY"
    },
    {
        "rating_id": "3",
        "review_id": "4",
        "product_id": "9",
        "percent": "80",
        "star": 4,
        "nickname": "YYYY"
    },
    {
        "rating_id": "2",
        "review_id": "4",
        "product_id": "9",
        "percent": "80",
        "star": 4,
        "nickname": "YYYY"
    }
],
"count": {
    "1": 0,
    "2": 1,
    "3": 1,
    "4": 2,
    "5": 2
},
"rating": {
    "all": 6,
    "avg": 3.8
}
}

Can someone please help to achieve the desired output?