clean up and add javadocs

Change-Id: I7f628106247de887cd91c4a4b4b55d3ebfa700c8
diff --git a/graphics/java/android/renderscript/Long3.java b/graphics/java/android/renderscript/Long3.java
index c6d7289..6ae837a 100644
--- a/graphics/java/android/renderscript/Long3.java
+++ b/graphics/java/android/renderscript/Long3.java
@@ -21,7 +21,7 @@
 
 
 /**
- *
+ * Class for exposing the native Renderscript long3 type back to the Android system.
  **/
 public class Long3 {
     public Long3() {