YAML is a superset of JSON. This means you can use JSON syntax for objects and arrays within a YAML document.

In your first example, you can just remove the | after the value: to keep the example value as an object.

The following are equivalent:

examples:
  singlePet:
    summary: Single pet
    description: A request containing a single pet
    value:
      {
        "pets" : [
          {
            "petType" : "DOG",
            "name" : "Ben"
          }
        ]
      }

examples:
  singlePet:
    summary: Single pet
    description: A request containing a single pet
    value:
      pets:
      - petType: DOG
        name: Ben

Alternatively, you can use externalValue to point to an external file containing sample JSON.

examples:
  singlePet:
    summary: Single pet
    description: A request containing a single pet
    externalValue: 'https://api.example.com/docs/examples/pet.json'

import io.swagger.v3.parser.OpenAPIV3Parser;
import io.swagger.v3.oas.models.media.Schema;
import io.swagger.oas.inflector.examples.models.Example;
import io.swagger.oas.inflector.examples.ExampleBuilder;
import com.fasterxml.jackson.databind.module.SimpleModule;
import io.swagger.oas.inflector.processors.JsonNodeExampleSerializer;
import io.swagger.util.Json;

OpenAPI swagger = new OpenAPIV3Parser().read("C:\\Users\\ABC\\Downloads\\Petstore-1.0.yaml")
Map<String, Schema> definitions = swagger.getComponents().getSchemas();
Schema model = definitions.get("Pet");
Example example = ExampleBuilder.fromSchema(model, definitions);
SimpleModule simpleModule = new SimpleModule().addSerializer(new JsonNodeExampleSerializer());
Json.mapper().registerModule(simpleModule);
String jsonExample = Json.pretty(example);
System.out.println(jsonExample);

Dependency for swagger inflector

compile group: 'io.swagger', name: 'swagger-inflector', version: '2.0.0'

Sometime i was also went through this issue and I solve them by using the online tools example : https://onlineyamltools.com/convert-yaml-to-json. that convert YAML structured file into JSON structured file .

but if you need a Javascript parser you can use js-yaml

you can use it to convert yaml to json with your js code.

According to the OpenAPI Specification,

An OpenAPI document that conforms to the OpenAPI Specification is itself a JSON object, which may be represented either in JSON or YAML format.

So feature-wise, there is no difference between using JSON or YAML. What YAML as a superset of JSON adds here is merely a different syntax. Using an example from the specification, these two documents are identical:

{
  "servers": [
    {
      "url": "https://development.gigantic-server.com/v1",
      "description": "Development server"
    },
    {
      "url": "https://staging.gigantic-server.com/v1",
      "description": "Staging server"
    },
    {
      "url": "https://api.gigantic-server.com/v1",
      "description": "Production server"
    }
  ]
}

and

servers:
- url: https://development.gigantic-server.com/v1
  description: Development server
- url: https://staging.gigantic-server.com/v1
  description: Staging server
- url: https://api.gigantic-server.com/v1
  description: Production server

The first document is valid JSON and valid YAML (since YAML is a superset of JSON). The second document is valid YAML and structurally identical to the first document.

So to answer the question about what the YAML superset adds here: It adds different syntax for specifying the same structures. Nothing more.

^{YAML does include some features that are not mappable to JSON, but they are irrelevant here because Swagger/OpenAPI doesn't use them.}