GW2v2GuildTreasurySlot  
  constructor(itemId: GW2ItemId, count: Int, neededBy: List<GW2v2GuildTreasurySlot.UpgradeRequirement>)
Parameters
itemId 
the item's ID
count
the amount of the item in the guild's treasury
neededBy 
the currently in-progress upgrades requiring the item