long getPendingNanos() {
    return pendingNanos.get();
  }
Returns the total amount of delay (in nanoseconds) that needs to be applied to subsequent work.
Alternatively this can be thought to capture the error between expected delay and actual
applied delay. This accounts for variance in the precision of the delay mechanism,
which may vary from platform to platform.
<p>
This is required for test purposes only.

@return the total amount of delay (in nanoseconds) that needs to be applied to subsequent work.
samza-core/src/main/java/org/apache/samza/util/ThrottlingScheduler.java