Fix checkstyle warnings

- Redundant 'public' modifier on interface method
- Redundant intialization of class member to null

Change-Id: Id08d0e4d199b55222fa00919fe2a6ed2522756ff
diff --git a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/TreeWalkVisitor.java b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/TreeWalkVisitor.java
index 5445b1b..3386fda 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/TreeWalkVisitor.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/uploadvalidator/TreeWalkVisitor.java
@@ -18,6 +18,6 @@
 
 public interface TreeWalkVisitor {
 
-  public void onVisit(TreeWalk tw);
+  void onVisit(TreeWalk tw);
 
 }
diff --git a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ListVisitedPathsFilter.java b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ListVisitedPathsFilter.java
index 282590b..b5672b0 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ListVisitedPathsFilter.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/uploadvalidator/ListVisitedPathsFilter.java
@@ -23,7 +23,7 @@
 import java.util.List;
 
 public class ListVisitedPathsFilter extends TreeFilter {
-  private List<String> visitedPaths = null;
+  private List<String> visitedPaths;
 
   public ListVisitedPathsFilter(List<String> visitedPaths) {
     super();