OpenAPI Hello World example

openapi.yaml

openapi: 3.0.0
info:
  title: Hello World
  version: 1.0.0
paths:
  /hello:
    get:
      parameters:
        - name: name
          in: query
          required: true
          schema:
            type: string
      responses:
        '200': 
          description: OK
          content:
            'application/json':
              schema:
                type: string