Updates a credential. A credential links an ID your customer sends with their usage (externalId) to a subscriber and a customer organization, so that usage is attributed to them. name, teamId, organizationId, subscriberId and externalId are required. What each field does: name, organizationId and subscriberId are replaced with what you send. externalId is replaced, unless you send back the masked value from GET (three dots and four characters), which keeps the current one. externalSecret is replaced when you send a non-empty value and kept otherwise. subscriptionIds replaces the linked subscriptions when you send a list, unlinks them all when you send an empty list, and keeps them when you leave it out or send null. tags replaces the tags when you send at least one, and keeps them otherwise. The credential ID and teamId cannot be changed.