Ephemeral storage reporting is in beta since Kubernetes 1.10 [1].  But for some reason it is not getting reported by 4.2 kubelets.  For an example of a 4.2 cluster without ephemeral-storage capacity reporting, see this 4.2.10 -> 4.2.12 update test [2]:

  $ curl -s https://storage.googleapis.com/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade/12620/artifacts/e2e-aws-upgrade/must-gather/quay-io-openshift-release-dev-ocp-v4-0-art-dev-sha256-a0dbe73b7831a8ddb9a2c58a560461d7c2c23a92231289a2104b93e7723c0eff/cluster-scoped-resources/core/nodes/ip-10-0-129-58.ec2.internal.yaml | yaml2json | jq .status.capacity | json2yaml
  attachable-volumes-aws-ebs: '39'
  cpu: '4'
  hugepages-1Gi: '0'
  hugepages-2Mi: '0'
  memory: 16419384Ki
  pods: '250'

Capacity reporting is working in 4.3, e.g. see this 4.2.12 -> 4.3.0-0.nightly-2020-01-02-141332 update test [3].

  $ curl -s https://storage.googleapis.com/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade/13437/artifacts/e2e-aws-upgrade/must-gather/quay-io-openshift-release-dev-ocp-v4-0-art-dev-sha256-c6c63e67c3d38a704c8695a40bb64b9975df2bda3f00c9379592cd5596126f2d/cluster-scoped-resources/core/nodes/ip-10-0-130-241.ec2.internal.yaml | yaml2json | jq .status.capacity | json2yaml
  attachable-volumes-aws-ebs: '39'
  cpu: '4'
  ephemeral-storage: 124768236Ki
  hugepages-1Gi: '0'
  hugepages-2Mi: '0'
  memory: 16419384Ki
  pods: '250'

In bug 1786315, we are taking the narrow fix of removing our reliance on the ephemeral-storage capacity reporting.  But there may be other consumers outside of the cluster-version operator who would like to have ephemeral-storage reporting in 4.2.z.

[1]: https://github.com/kubernetes/enhancements/issues/361
[2]: https://prow.svc.ci.openshift.org/view/gcs/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade/12620
[3]: https://prow.svc.ci.openshift.org/view/gcs/origin-ci-test/logs/release-openshift-origin-installer-e2e-aws-upgrade/13437