code: public ResourcePoolsBuilder heap(long size, ResourceUnit unit) {
      return with(ResourceType.Core.HEAP, size, unit, false);
    }
docs: Convenience method to add a {@link org.ehcache.config.ResourceType.Core#HEAP heap} pool.
  
  @param size the pool size
  @param unit the pool size unit
  @return a new builder with the added pool
  
  @throws IllegalArgumentException if the set of resource pools already contains a heap resource