For a filter that uses EVENT type, a comma-separated string that specifies one event: PUSH, PULL_REQUEST_CREATED, PULL_REQUEST_UPDATED, PULL_REQUEST_REOPENED. PULL_REQUEST_MERGED works with GitHub & GitHub Enterprise only. For a filter that uses any of the other filter types, a regular expression.
The webhook filter group's type. Valid values for this parameter are: EVENT, BASE_REF, HEAD_REF, ACTOR_ACCOUNT_ID, FILE_PATH, COMMIT_MESSAGE. At least one filter group must specify EVENT as its type.