SSU: Add note about skew threshold

router/java/src/net/i2p/router/transport/udp/PacketHandler.java

@@ -46,7 +46,11 @@ class PacketHandler {
     private static final int MAX_QUEUE_SIZE = 192;
     private static final int MIN_NUM_HANDLERS = 1;  // unless < 32MB
     private static final int MAX_NUM_HANDLERS = 1;
-    /** let packets be up to 30s slow */
+    /**
+     *  Let packets be up to this much skewed.
+     *  This is the same limit as in InNetMessagePool's MessageValidator.
+     *  There's no use making it any larger, as messages will just be thrown out there.
+     */
     private static final long GRACE_PERIOD = Router.CLOCK_FUDGE_FACTOR + 30*1000;
     private static final long MAX_SKEW = 90*24*60*60*1000L;