Merge pull request #1692 from daspilker/JENKINS-28292

[JENKINS-28292] fixed synchronization issue when setting JDK installations

core/src/main/java/hudson/model/JDK.java

@@ -166,11 +166,8 @@ public final class JDK extends ToolInstallation implements NodeSpecific<JDK>, En
             return Jenkins.getInstance().getJDKs().toArray(new JDK[0]);
         }
 
-        // this isn't really synchronized well since the list is Hudson.jdks :(
-        public @Override synchronized void setInstallations(JDK... jdks) {
-            List<JDK> list = Jenkins.getInstance().getJDKs();
-            list.clear();
-            list.addAll(Arrays.asList(jdks));
+        public @Override void setInstallations(JDK... jdks) {
+            Jenkins.getInstance().setJDKs(Arrays.asList(jdks));
         }
 
         @Override

core/src/main/java/jenkins/model/Jenkins.java

@@ -1640,12 +1640,23 @@ public class Jenkins extends AbstractCIBase implements DirectlyModifiableTopLeve
         return Messages.Hudson_DisplayName();
     }
 
-    public List<JDK> getJDKs() {
+    public synchronized List<JDK> getJDKs() {
         if(jdks==null)
             jdks = new ArrayList<JDK>();
         return jdks;
     }
 
+    /**
+     * Replaces all JDK installations with those from the given collection.
+     *
+     * Use {@link hudson.model.JDK.DescriptorImpl#setInstallations(JDK...)} to
+     * set JDK installations from external code.
+     */
+    @Restricted(NoExternalUse.class)
+    public synchronized void setJDKs(Collection<? extends JDK> jdks) {
+        this.jdks = new ArrayList<JDK>(jdks);
+    }
+
     /**
      * Gets the JDK installation of the given name, or returns null.
      */
@@ -2852,8 +2863,7 @@ public class Jenkins extends AbstractCIBase implements DirectlyModifiableTopLeve
 
             systemMessage = Util.nullify(req.getParameter("system_message"));
 
-            jdks.clear();
-            jdks.addAll(req.bindJSONToList(JDK.class,json.get("jdks")));
+            setJDKs(req.bindJSONToList(JDK.class, json.get("jdks")));
 
             boolean result = true;
             for (Descriptor<?> d : Functions.getSortedDescriptorsForGlobalConfigUnclassified())