Steps to reproduce:

1. Create a discovery rule that defines an item and trigger that contains {#MACRO1} in their names ie "This is the name {MACRO1}".
2. Send a discovery packet where {#MACRO1} contains NULL ie "".
3. Confirm item and trigger have been created.

Result:
You will see that the item name contains "This is the name []" and the trigger name contains "This is the name [ ]" - Ie there is a space in the trigger name as I believe it is not substituted with a NULL and a space instead.

Expected:
What I would expect is the "" is treated the same and the names do no include a space for an empty macro....