query BoardBlockingEpics($fullPath: ID!, $iid: ID) {
  group(fullPath: $fullPath) {
    id
    issuable: epic(iid: $iid) {
      id
      blockingIssuables: blockedByEpics {
        nodes {
          id
          iid
          title
          reference(full: true)
          webUrl
        }
      }
    }
  }
}