From 6d93cbcd677c2675cfccc52bb69ea0046d821fc4 Mon Sep 17 00:00:00 2001
From: manusa <marc@marcnuri.com>
Date: Thu, 18 Feb 2021 11:07:41 +0100
Subject: [PATCH] fix: Replace double-checked locking idiom with
 initialization-on-demand holder idiom

- https://rules.sonarsource.com/java/tag/multi-threading/RSPEC-2168
- https://en.wikipedia.org/wiki/Initialization-on-demand_holder_idiom
---
 .../client/internal/readiness/Readiness.java          | 11 ++++-------
 .../client/internal/readiness/OpenShiftReadiness.java | 11 ++++-------
 2 files changed, 8 insertions(+), 14 deletions(-)

diff --git a/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/internal/readiness/Readiness.java b/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/internal/readiness/Readiness.java
index 69708bbdc94..9a6b52331f2 100644
--- a/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/internal/readiness/Readiness.java
+++ b/kubernetes-client/src/main/java/io/fabric8/kubernetes/client/internal/readiness/Readiness.java
@@ -49,15 +49,12 @@ public class Readiness {
   protected static final String READINESS_APPLICABLE_RESOURCES =
     "Node, Deployment, ReplicaSet, StatefulSet, Pod, ReplicationController";
 
-  private static Readiness instance;
+  private static class ReadinessHolder {
+    public static final Readiness INSTANCE = new Readiness();
+  }
 
   public static Readiness getInstance() {
-    if (instance == null) {
-      synchronized (Readiness.class) {
-        instance = new Readiness();
-      }
-    }
-    return instance;
+    return ReadinessHolder.INSTANCE;
   }
 
   /**
diff --git a/openshift-client/src/main/java/io/fabric8/openshift/client/internal/readiness/OpenShiftReadiness.java b/openshift-client/src/main/java/io/fabric8/openshift/client/internal/readiness/OpenShiftReadiness.java
index 03976faea61..a0e7db59c8e 100644
--- a/openshift-client/src/main/java/io/fabric8/openshift/client/internal/readiness/OpenShiftReadiness.java
+++ b/openshift-client/src/main/java/io/fabric8/openshift/client/internal/readiness/OpenShiftReadiness.java
@@ -27,15 +27,12 @@ public class OpenShiftReadiness extends Readiness {
   private static final String OPENSHIFT_READINESS_APPLICABLE_RESOURCES = READINESS_APPLICABLE_RESOURCES +
     ", " + "DeploymentConfig";
 
-  private static OpenShiftReadiness instance;
+  private static class OpenShiftReadinessHolder {
+    public static final OpenShiftReadiness INSTANCE = new OpenShiftReadiness();
+  }
 
   public static OpenShiftReadiness getInstance() {
-    if (instance == null) {
-      synchronized (OpenShiftReadiness.class) {
-        instance = new OpenShiftReadiness();
-      }
-    }
-    return instance;
+    return OpenShiftReadinessHolder.INSTANCE;
   }
 
   @Override