# JSON

Any JSON-based message **MUST** conform to the following rules:

1. All JSON field names **MUST** follow the [Naming Conventions ](../rest-api-guidelines/evolution/naming-conventions.md)\(`camelCase`, American English, etc.\)
2. Field names **MUST** be ASCII alpha num characters, underscore \(`_`\) or dollar sign \(`$`\)
3. Boolean fields **MUST NOT** be of `null` value
4. Fields with `null` value **SHOULD** be omitted
5. Empty arrays and objects **SHOULD NOT**  be `null` \(use `[]` or `{}` instead\)
6. Array field names **SHOULD** be plural \(e.g. `"orders": []`\)

## Validation
All API designers **MUST** validate the definition of the payloads in requests/responses with the [JSON Schema](https://json-schema.org/) for the defined structure prior to the publication of the API Contract in SwaggerHub.

The publication of the JSON schema corresponding to the expected payloads in the bodies of requests and responses **SHOULD** be kept up to date according to the evolution of the API.