better to define a corresponding descriptor type for backward compatibility...

better to define a corresponding descriptor type for backward compatibility and methods like display name.

core/src/main/java/hudson/matrix/MatrixConfigurationSorter.java

@@ -37,7 +37,8 @@ public abstract class MatrixConfigurationSorter extends AbstractDescribableImpl<
      */
     public abstract String getErrorFormMessage();
 
-    public static List<MatrixConfigurationSorter> all() {
-        return Hudson.getInstance().getExtensionList(MatrixConfigurationSorter.class);
+    @Override
+    public MatrixConfigurationSorterDescriptor getDescriptor() {
+        return (MatrixConfigurationSorterDescriptor)super.getDescriptor();
     }
 }

core/src/main/java/hudson/matrix/MatrixConfigurationSorterDescriptor.java

+package hudson.matrix;
+
+import hudson.DescriptorExtensionList;
+import hudson.model.Descriptor;
+import jenkins.model.Jenkins;
+
+/**
+ * @author Kohsuke Kawaguchi
+ */
+public abstract class MatrixConfigurationSorterDescriptor extends Descriptor<MatrixConfigurationSorter> {
+    protected MatrixConfigurationSorterDescriptor(Class<? extends MatrixConfigurationSorter> clazz) {
+        super(clazz);
+    }
+
+    protected MatrixConfigurationSorterDescriptor() {
+    }
+
+    /**
+     * Returns all the registered {@link AxisDescriptor}s.
+     */
+    public static DescriptorExtensionList<MatrixConfigurationSorter,MatrixConfigurationSorterDescriptor> all() {
+        return Jenkins.getInstance().<MatrixConfigurationSorter,MatrixConfigurationSorterDescriptor>getDescriptorList(MatrixConfigurationSorter.class);
+    }    
+}