Json validation — json-validation

# Local demonstration: go run ./cmd/hookway serve --config examples/json-validation.yaml
# POST /orders with: {"order_id":9007199254740993,"customer":{"email":"dev@example.com"}}
# This example accepts public traffic; put an auth node before envelope in production.
server:
  addr: ":8080"
  max_body_bytes: 1048576
flows:
  orders:
    nodes:
      - {id: in, type: http_trigger, path: /orders, methods: [POST]}
      - {id: body, type: read_body, max_bytes: 1048576}
      - {id: public_demo, type: no_auth}
      - {id: event, type: envelope, body_format: json}
      - id: check
        type: json_validate
        schema:
          $schema: http://json-schema.org/draft-07/schema#
          type: object
          required: [order_id, customer]
          additionalProperties: false
          properties:
            order_id: {type: integer, minimum: 1}
            customer: {$ref: '#/definitions/customer'}
          definitions:
            customer:
              type: object
              required: [email]
              properties:
                email: {type: string, format: email}
              additionalProperties: false
        # Strict by default. Enable only when this conversion is intentional:
        # coercions: [{path: order_id, type: integer}]
      - {id: accepted, type: respond, status: 200, body: "Valid order"}
    edges: [in>body, body>public_demo, public_demo>event, event>check, check>accepted]