allow, but discourage, requestBody for GET, HEAD, DELETE (#2117)

Author: n2ygk

versions/3.1.0.md

@@ -851,7 +851,7 @@ Field Name | Type | Description
 <a name="operationExternalDocs"></a>externalDocs | [External Documentation Object](#externalDocumentationObject) | Additional external documentation for this operation.
 <a name="operationId"></a>operationId | `string` | Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is **case-sensitive**. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions.
 <a name="operationParameters"></a>parameters | [[Parameter Object](#parameterObject) \| [Reference Object](#referenceObject)] | A list of parameters that are applicable for this operation. If a parameter is already defined at the [Path Item](#pathItemParameters), the new definition will override it but can never remove it. The list MUST NOT include duplicated parameters. A unique parameter is defined by a combination of a [name](#parameterName) and [location](#parameterIn). The list can use the [Reference Object](#referenceObject) to link to parameters that are defined at the [OpenAPI Object's components/parameters](#componentsParameters).
-<a name="operationRequestBody"></a>requestBody | [Request Body Object](#requestBodyObject) \| [Reference Object](#referenceObject) | The request body applicable for this operation.  The `requestBody` is only supported in HTTP methods where the HTTP 1.1 specification [RFC7231](https://tools.ietf.org/html/rfc7231#section-4.3.1) has explicitly defined semantics for request bodies.  In other cases where the HTTP spec is vague, `requestBody` SHALL be ignored by consumers.
+<a name="operationRequestBody"></a>requestBody | [Request Body Object](#requestBodyObject) \| [Reference Object](#referenceObject) | The request body applicable for this operation.  The `requestBody` is fully supported in HTTP methods where the HTTP 1.1 specification [RFC7231](https://tools.ietf.org/html/rfc7231#section-4.3.1) has explicitly defined semantics for request bodies.  In other cases where the HTTP spec is vague (such as [GET](https://tools.ietf.org/html/rfc7231#section-4.3.1), [HEAD](https://tools.ietf.org/html/rfc7231#section-4.3.2) and [DELETE](https://tools.ietf.org/html/rfc7231#section-4.3.5)), `requestBody` is permitted but does not have well-defined semantics and SHOULD be avoided if possible.
 <a name="operationResponses"></a>responses | [Responses Object](#responsesObject) | **REQUIRED**. The list of possible responses as they are returned from executing this operation.
 <a name="operationCallbacks"></a>callbacks | Map[`string`, [Callback Object](#callbackObject) \| [Reference Object](#referenceObject)] | A map of possible out-of band callbacks related to the parent operation. The key is a unique identifier for the Callback Object. Each value in the map is a [Callback Object](#callbackObject) that describes a request that may be initiated by the API provider and the expected responses. The key value used to identify the callback object is an expression, evaluated at runtime, that identifies a URL to use for the callback operation.
 <a name="operationDeprecated"></a>deprecated | `boolean` | Declares this operation to be deprecated. Consumers SHOULD refrain from usage of the declared operation. Default value is `false`.