code: public final long plus(final long value, @Nonnull final TimeUnit timeUnit) {
          return this.millis.addAndGet(timeUnit.toMillis(value));
      }
docs: Add the specified amount of time to the current clock.
  
  @param value The numeric value to add to the clock after converting
  based on the provided {@code timeUnit}.
  @param timeUnit The time unit that {@code value} is measured in.
  @return The time after being adjusted by the provided offset.