MED received

A PIX MED (special refund) was opened by the payer's bank.

The HTTP body is this object exactly — there is no envelope and no type field. The event name is delivered in the X-Webhook-Event header. Most optional fields arrive as an explicit null; a few keys are dropped from the JSON entirely when unset, and those are marked as such below. Read values with a null-safe accessor rather than testing key presence.