// called from `structFromUnstructured`.
func (c *fromUnstructuredContext) pushMatchedKeyTracker() {
	if !c.returnUnknownFields {
		return
	}

	c.matchedKeys = append(c.matchedKeys, nil)
}

// recordMatchedKey initializes the last element of matchedKeys
// (if needed) and sets 'key'. This should only be called from
// `structFromUnstructured`.