use a dedicated List type

git-svn-id: https://hudson.dev.java.net/svn/hudson/trunk/hudson/main@9331 71c3de6d-444a-0410-be80-ed276b4c234a

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

 package hudson.model;
 
 import hudson.ExtensionPoint;
+import hudson.security.SecurityRealm;
+import hudson.util.DescriptorList;
 
 import java.util.List;
 import java.util.ArrayList;
@@ -24,5 +26,8 @@ public abstract class SlaveStartMethod implements Describable<SlaveStartMethod>,
 
     public abstract void start(Slave.ComputerImpl computer, Slave slave, OutputStream launchLog, Logger logger);
 
-    public static final List<Descriptor<SlaveStartMethod>> LIST = new ArrayList<Descriptor<SlaveStartMethod>>();
+    /**
+     * All registered {@link SlaveStartMethod} implementations.
+     */
+    public static final DescriptorList<SlaveStartMethod> LIST = new DescriptorList<SlaveStartMethod>();
 }