This Babel plugin is for marking Forge UI JSX components with unique key (property) __auxId.

The purpose of the key is to be consistent between renders, even when the code around it is inconsistent like this:

{showButtonOne && <Button text="Hello" />}
<Button text="World" />

Without this Babel plugin, the "World" button may be marked Button.0 or Button.1, depending on the value of showButtonOne.