Remove default constructors from static utility classes.

Change-Id: Id8dc55a30a03e1da87500b66c429de9268033b9e
http://b/3344646
diff --git a/core/java/android/util/DebugUtils.java b/core/java/android/util/DebugUtils.java
index 65fc35c..7e3c855 100644
--- a/core/java/android/util/DebugUtils.java
+++ b/core/java/android/util/DebugUtils.java
@@ -20,9 +20,11 @@
 import java.lang.reflect.InvocationTargetException;
 
 /**
- * <p>Various utilities for debugging and logging.</p> 
+ * <p>Various utilities for debugging and logging.</p>
  */
 public class DebugUtils {
+    /** @hide */ public DebugUtils() {}
+
     /**
      * <p>Filters objects against the <code>ANDROID_OBJECT_FILTER</code>
      * environment variable. This environment variable can filter objects