BlockingCell now consistently uses System.nanoTime rather than sometimes using System.currentTimeMillis

Author: dhakimTRX

src/main/java/com/rabbitmq/utility/BlockingCell.java

@@ -66,9 +66,9 @@ public synchronized T get(long timeout) throws InterruptedException, TimeoutExce
         if (timeout < 0)
             throw new AssertionError("Timeout cannot be less than zero");
 
-        long maxTime = System.currentTimeMillis() + timeout;
-        long now;
-        while (!_filled && (now = System.currentTimeMillis()) < maxTime) {
+        long now = System.nanoTime() / NANOS_IN_MILLI;
+        long maxTime = now + timeout;
+        while (!_filled && (now = (System.nanoTime() / NANOS_IN_MILLI)) < maxTime) {
             wait(maxTime - now);
         }