MetadataPatch

Writing metadata. An update (PATCH) merges the keys with the existing ones: the value "" or null removes a key, and {} changes nothing. On create and replace (POST, PUT), the object is set as a whole, and "" and null values are skipped. The limits are those of Metadata. A violation returns 400 api.metadata_invalid with details.key and details.reason: too_many_keys, key_invalid, value_too_long, too_large or value_invalid (the value is not a string).