Add annotation key definitions for bandwidth and optical waves.

Change-Id: Ia0e3b638cd0f756e427c4c0d6d75b4e2d65002fc

@@ -30,6 +30,16 @@ public final class AnnotationKeys {
     public static final String LATENCY = "latency";
 
     /**
+     * Annotation key for bandwidth.
+     */
+    public static final String BANDWIDTH = "bandwidth";
+
+    /**
+     * Annotation key for the number of optical waves.
+     */
+    public static final String OPTICAL_WAVES = "optical.waves";
+
+    /**
      * Returns the value annotated object for the specified annotation key.
      * The annotated value is expected to be String that can be parsed as double.
      * If parsing fails, the returned value will be 1.0.