Java Swing: How can you alter the margins in Nimbus Look and Feel

Question

I'm trying to use Nimbus Look and Feel and I can't simply plug it in to replace other Look and feel because it adds some external padding around each component.

So, I would like to remove this padding. This is the list of defaults that can be changed, however the following code changes nothing.

UIManager.put("Button.contentMargins", new Insets(0, 0, 0, 0));

Other values are working as expected.

How can I remove this padding?

EDIT

I believe content margins is referring to the internal padding.

EDIT

Looking at the source code the external padding seems to be hard-coded. I believe it's added to allow for the focus selection property.

Should this be considered a bug? No other L&F does this, and with this extra padding it's not possible to reuse the same layout (as previous layouts all will be assuming no padding).