1. Vulnerability Description

• When defining an empty collection, it is better performance to declare it explicitly.

2. Vulnerability Countermeasure

• Most immutable collections implement empty as a singleton.
• If you explicitly create a collection using empty, you can reuse empty to reduce the use of heap space, and there is an advantage in operation performance as there is no runtime length check.

3. Sample Code

• Before

Map[K,V]()
Seq[T]()
Set[T]()

• After

Map.empty[K,V]
Seq.empty[T]
Set.empty[T]