Expand macro: Missing keyboard support

Issue Summary

The interactive element such as "Click here to expand..." is not operable with keyboard.

Steps to Reproduce

1. Open "Confluence DC" page.
2. Navigate to "Insert" expand collapse button and activate it.
3. Select the "Expand" macro option.
4. Ensure that "Expand" macro has been appeared on the screen.
5. Type the data and navigate to "Publish" button and activate it.
6. Check that Confluence DC page has been created.
7. Navigate to the "Click here to Expand..." element.
8. Using keyboard, try to access it.
9. Notice that the above mentioned element is not accessible using keyboard.

Actual Results

The keyboard support is missing for "Click here to expand...' as no role (i.e. link or button) provided for this element programmatically.

This made it difficult for screen reader and keyboard-only users to access the functionality.

Expected Results

Apply the following changes

• Provide native <button> element for "Click here to expand". OR Provide role "button" to the mentioned element.
• Specify aria-expanded attribute to the <button> element.
• Ensure that the value of aria-expanded attribute changes to "true" and "false" as per user interaction in expanded/collapsed state respectively.
• Ensure that all the page functionality is available for all users irrespective of the device being used.

Note: As per suggestion from customer there should be option which allows the user to set display to expanded by default (as the "UI Expand" macro does).

Refer to the following links for more Information about Accessible accordions

https://www.w3.org/WAI/ARIA/apg/patterns/accordion/examples/accordion/ 

https://hello.atlassian.net/wiki/spaces/A11Y/pages/1383354098/Accordions 

Screenshot

Workaround

Currently there is no known workaround for this behavior. A workaround will be added here when available