Context for a subscription operation, carrying either an HTTP request context or a WebSocket connection info.
The SSE path supplies requestContext; the WS path supplies
connection. Using this type (instead of IRequestContext)
prevents the WS path from silently handing resolvers an empty context.
readonly
optional
requestContext: IRequestContext
The HTTP request context (supplied by the SSE path).
readonly
optional
connection: GraphqlConnectionInfo
The WebSocket connection info (supplied by the WS path).