Setting header text of a DisclosurePanel dynamically while preserving the arrow icon?

I'd like to set the text in DisclosurePanel's header without having to re-construct the image/icon used by the default header.

Using customHeader means the arrow-icon is lost, in other words tha开发者_如何学Ct seems like unreasonable amount of extra work.

EDIT: There's actually method for that, getHeaderTextAccessor(String)

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getHeaderTextAccessor(String)