code: public FlakeIdGeneratorConfig setPrefetchCount(int prefetchCount) {
          checkTrue(prefetchCount > 0 && prefetchCount <= MAXIMUM_PREFETCH_COUNT,
                  "prefetch-count must be 1.." + MAXIMUM_PREFETCH_COUNT + ", not " + prefetchCount);
          this.prefetchCount = prefetchCount;
          return this;
      }
docs: Sets how many IDs are pre-fetched on the background when one call to
  {@link FlakeIdGenerator#newId()} is made. Default is 100.
  <p>
  This setting pertains only to {@link FlakeIdGenerator#newId newId} calls made on the member
  that configured it.
  
  @param prefetchCount the desired prefetch count, in the range 1..100,000.
  @return this instance for fluent API