Sidebar Header doesn't allow text?

[ryrythomas]

When you create a Sidebar there is clearly a header section, which has the "X" at the right by default.
I can't find a way (other than using some css hackery ::after) to put a text string in the header. Why isn't there a <template #header> section available? the real estate is already there and just doesn't seem to be accessible. Am I missing something? Documentation doesn't seem to provide any mention of a header.

[tugce.kucukoglu]

Sidebar component does not have header template. But it can show the content with default template. Closing icon comes from by design.