grpc-core: combined epoch seconds and nanos changes in TimeProvider

core/src/main/java/io/grpc/internal/TimeProvider.java

@@ -33,7 +33,7 @@ public long currentTimeNanos() {
       Instant instant = Instant.now();
       int nanos = instant.getNano();
       long epochSeconds = instant.getEpochSecond();
-      return nanos + epochSeconds;
+      return Long.parseLong("" + epochSeconds + nanos);
     }
   };
 }