Remove redundant 'static' modifiers

enums, interfaces, and field members in interfaces are by default
static, so don't need to be explicitly declared so.

Change-Id: I29270c28be30965767519ad0105a7d93a24e0ab4

gerrit-server/src/main/java/com/google/gerrit/server/util/TreeFormatter.java

@@ -19,7 +19,7 @@ import java.util.SortedSet;
 
 public class TreeFormatter {
 
-  public static interface TreeNode {
+  public interface TreeNode {
     String getDisplayName();
     boolean isVisible();
     SortedSet<? extends TreeNode> getChildren();