OpenShift Logging ElasticSearch cluster not forming due to: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target

Issue

• ElasticSearch pods are failing to start due to:

  [2019-02-06 19:57:30,681][WARN ][io.fabric8.elasticsearch.discovery.kubernetes.KubernetesUnicastHostsProvider] [logging-es-data-master-35ny545c] Exception caught during discovery: An error has occurred.
  io.fabric8.kubernetes.client.KubernetesClientException: An error has occurred.
    at io.fabric8.kubernetes.client.KubernetesClientException.launderThrowable(KubernetesClientException.java:57)
    at io.fabric8.kubernetes.client.dsl.base.BaseOperation.list(BaseOperation.java:385)
    at io.fabric8.kubernetes.client.dsl.base.BaseOperation.list(BaseOperation.java:57)
    at io.fabric8.elasticsearch.cloud.kubernetes.KubernetesAPIServiceImpl.pods(KubernetesAPIServiceImpl.java:47)
    at io.fabric8.elasticsearch.discovery.kubernetes.KubernetesUnicastHostsProvider.readNodes(KubernetesUnicastHostsProvider.java:190)
        ...
  Caused by: javax.net.ssl.SSLHandshakeException: sun.security.validator.ValidatorException: PKIX path building failed: sun.security.provider.certpath.SunCertPathBuilderException: unable to find valid certification path to requested target
    at sun.security.ssl.Alerts.getSSLException(Alerts.java:192)
    at sun.security.ssl.SSLSocketImpl.fatal(SSLSocketImpl.java:1946)
    at sun.security.ssl.Handshaker.fatalSE(Handshaker.java:316)
        ...