We should update all our examples to use https://schema.org/

Several years ago we established this as a direction, see https://schema.org/docs/faq.html#19

There is a general trend towards using 'https' more widely, and you can already write 'https://schema.org' in your structured data. Over time we will migrate the schema.org site itself towards using https: as the default version of the site and our preferred form in examples. However 'http://schema.org' -based URLs in structured data markup will remain widely understood for the forseeable future and there should be no urgency about migrating existing data. This is a lengthy way of saying that both 'https://schema.org' and 'http://schema.org' are fine.

@tmarshbing @tilid @nicolastorzec @scor @rvguha

/cc @RichardWallis

If there are no objections I think we should set this in motion asap