I'm trying to create a custom InventoryView. I was able to do this back in 1.12 without issue. Unfortunately, in version 1.15.2, something is not working right. Maybe I do not understand the workflow for when things call 'player.openInventory(customInventoryView)'

Anyways, I have created a simple test plugin to experiment with and demonstrate the issue.

I have attached the full code.

 CustomInvView is the custom InventoryView.

SimpleTest is the main plugin interface and implements the command.

The plugin is very simple. I have a command 'invtest' that when called it will create a new CustomInvView and have the player open that inventory. It should spawn a top inventory with 54 item slots. Instead it only opens an inventory with 27 slots. What am I missing in this version of spigot as I was not having this issue in earlier versions!

And here is a screenshot showing that smaller inventory.

A couple interesting points.
1) If I print the size of the top inventory for the CustomInvView it prints the correct value of 54.
2) If I have the player specifically open the topInventory from the CustomInvView, then it looks right. However I do not want to do this because I want to detect the CustomInvView within an InventoryClickEvent as shown below:

Example of how I plan on using the CustomInvView:

@EventHandler
 public void inventoryClick(InventoryClickEvent e)
 { 
 if (e.getView() instanceof CustomInvView)
{ CustomInvView customInvView = (CustomInvView)e.getView(); // Do things that are specific to the custom inv }
}

Any ideas on why the CustomInvView does not have the requested 54 item slots?