Creating a property holder

To create a property holder (UML class stereotyped as «Anything»)

Create a UML class (named "Thing" below).
A UML class.
Right-click on the UML class and select Stereotype.
Selecting the class' Stereotype shortcut menu.
Type "Anything" in the search box.
Select the stereotype "Anything".
Click Apply.

Selecting the Anything stereotype for the class.
The stereotype will be applied to the class.

The Anything stereotype applied to the UML class.