Magento 2 API want to implement product details based on custom format?

Question

Magento 2 how to implement configurable product collection formate as shown blow can you please suggest me.

Required format:-

{
 "id": 10,
 "name": "Hello",
 "sku": "hello"
 "description": "Lorem Ipsum is simply dummy text of the printing and typesetting industry. Lorem Ipsum has been the industry's standard dummy text ever since the 1500s, when an unknown printer took a galley of type and scrambled it to make a type specimen book."
 "brand": "Nutridiet",
 "position": 1,
 "url_key": "null",
 "url": "http://hostmname.com/hello.html",
 "express_delivery":"yes",
 "collection":"no",
 "status":1,
 "is_offer": "yes",
 "offer_text": "Buy 1 get 1 free",
 "store_id": 1
 "children_data": [
 {
 "id": 3,
 "parent_id": 2,
 "name": "Hello Test 2",
 "sku": "Hello-Test-2",
 "status": 1,
 "position": 1,
 "weight": "500",
 "price": 7.50,
 "special_price": 5,
 },
 {
 "id": 4,
 "parent_id": 2,
 "name": "Hello",
 "sku": "Hello-Test-3",
 "status": 1,
 "position": 2,
 "weight": "1.00",
 "price": 15,
 "special_price": ,
 },
 {
 "id": 5,
 "parent_id": 2,
 "name": "Hello-Test-4",
 "sku": "Hello-Test-5",
 "status": 1,
 "position": 3,
 "weight": "1.00",
 "price": 20,
 "special_price": ,
 }
 ]
}

default Magento 2 existing format:

Note:- As of now by default Magento 2 providing the format is

 "id": 82,
 "sku": "Jai",
 "name": "javan",
 "attribute_set_id": 4,
 "price": 0,
 "status": 1,
 "visibility": 4,
 "type_id": "configurable",
 "created_at": "2017-12-13 06:05:03",
 "updated_at": "2017-12-13 06:05:03",
 "product_links": [],
 "tier_prices": [],
 "custom_attributes": [
 {
 "attribute_code": "meta_title",
 "value": "Onions17"
 },
 {
 "attribute_code": "meta_keyword",
 "value": "Onions17"
 },
 {
 "attribute_code": "meta_description",
 "value": "Onions17 "
 },
 {
 "attribute_code": "image",
 "value": "/o/n/onion-05_copy_9_1.png"
 },
 {
 "attribute_code": "small_image",
 "value": "/o/n/onion-05_copy_9_1.png"
 },
 {
 "attribute_code": "thumbnail",
 "value": "/o/n/onion-05_copy_9_1.png"
 },
 {
 "attribute_code": "options_container",
 "value": "container2"
 },
 {
 "attribute_code": "required_options",
 "value": "1"
 },
 {
 "attribute_code": "has_options",
 "value": "1"
 },
 {
 "attribute_code": "url_key",
 "value": "onions17"
 },
 {
 "attribute_code": "gift_message_available",
 "value": "2"
 },
 {
 "attribute_code": "tax_class_id",
 "value": "2"
 }
 ]
 }

• Khoa Truong: Why don't you add it to extension attributes?
• Nagaraju Kasa: thanks for your reply @KhoaTruongDinh let me know is it possible to add custom key and value?
• Khoa Truong: What's your Magento version? I cannot find /V1/configurable/product on my Magento version 2.2.2.
• Nagaraju Kasa: actually i am using 2.1.7 i have customized code with custom url please check the code github.com/NagarajuKasa/Magento2Notes/blob/master/…
• Nagaraju Kasa: I hope you will understood the concept now am i correct?