Add to openshift client plugin config

openshift-client-plugin.groovy

import jenkins.model.Jenkins

import com.openshift.jenkins.plugins.OpenShift
import net.sf.json.JSONObject
import net.sf.json.JSONArray
import org.kohsuke.stapler.Stapler
import org.kohsuke.stapler.RequestImpl
import javax.servlet.http.HttpServletRequest

def httpServletRequest = [
  getRequestURI: { null }
] as javax.servlet.http.HttpServletRequest

def servletConfig = [
  getServletContext: { Jenkins.getInstance().servletContext },
  getInitParameter: { null },
  getServletName: { "" }
] as javax.servlet.ServletConfig

Stapler stapler = new Stapler()
stapler.init(servletConfig)

RequestImpl requestImpl = new RequestImpl(stapler, httpServletRequest, [] as java.util.List<org.kohsuke.stapler.AncestorImpl>, null)

JSONObject cluster1 = new JSONObject();
cluster1.put("name", "cluster1")
cluster1.put("serverUrl", "https://cluster:8443")
cluster1.put("serverCertificateAuthority", "cat from file")

JSONArray clusterConfigs = new JSONArray()
clusterConfigs.add(cluster1)

JSONObject openshift = new JSONObject()
openshift.put("clusterConfigs", clusterConfigs)

JSONObject json = new JSONObject()
json.put("openshift", openshift)

def openshiftDSL = Jenkins.getInstance().getDescriptor("com.openshift.jenkins.plugins.OpenShift")
openshiftDSL.configure(requestImpl, json)