code: @Nullable
      public Integer getWTimeout(final TimeUnit timeUnit) {
          notNull("timeUnit", timeUnit);
          return wTimeoutMS == null ? null : (int) timeUnit.convert(wTimeoutMS, TimeUnit.MILLISECONDS);
      }
docs: Gets the wTimeout in the given time unit.
  
  @param timeUnit the non-null time unit for the result
  @return the WTimeout, which may be null if a wTimeout has not been specified
  @since 3.2
  @mongodb.driver.manual core/write-concern/#timeouts wTimeout