dataset and group are slugified, so two of either can collapse to one
name. group is creates for the watcher the creates-only definitions
share, or a definition name for the update watcher that definition has to
itself. Throws when tag is not a valid engine tag, or group falls
outside EMITTED_NAME_PATTERN.
datasetandgroupare slugified, so two of either can collapse to one name.groupiscreatesfor the watcher the creates-only definitions share, or a definition name for the update watcher that definition has to itself. Throws whentagis not a valid engine tag, orgroupfalls outside EMITTED_NAME_PATTERN.