Bug - `react-styles` - When the `css` helper has no valid `className`s, it still includes the attribute when rendered

[logonoff]

Describe the problem
A clear and concise description of the problem. Which components are affected?

A FlexItem with no props renders as

<div class="">
</div>

Expected behavior
A clear and concise description of the expected behavior.

The class="" isn't there

Is this issue blocking you?
List the workaround if there is one.

No

What is your product and what release date are you targeting?

OCP 4.19