There is a one-off xml:lang attribute on an Activity example. JSON will not know what to make of such attributes, and neither does OpenAPI; I'm deleting it, and I suggest that SIF-NA delete any such instances they have as well. XML is liberal in sprinkling xml:... attributes in its schemas as grandfathered with XSD, but we can't have JSON being similarly liberal.
There is a one-off xml:lang attribute on an Activity example. JSON will not know what to make of such attributes, and neither does OpenAPI; I'm deleting it, and I suggest that SIF-NA delete any such instances they have as well. XML is liberal in sprinkling xml:... attributes in its schemas as grandfathered with XSD, but we can't have JSON being similarly liberal.