No changesets causes API validation error

[pnorman]

If inputting a custom API URL, JOSM makes a request to /api/0.6/changesets. If the API server in question has no changesets, it does not like the response, which is as below

<osm version="0.6" generator="OpenStreetMap server" copyright="OpenStreetMap and contributors" attribution="http://www.openstreetmap.org/copyright" license="http://opendatacommons.org/licenses/odbl/1-0/"/>

It remains possible to set the API in advanced preferences, which bypasses the check.

JOSM is also issuing the changesets call before a capabilities call, which seems the wrong way around.

[Don-vip]

Replying to pnorman:

JOSM is also issuing the changesets call before a capabilities call, which seems the wrong way around.

This is intended:

Note: it fetches a list of changesets instead of the much smaller capabilities because - strangely enough -
an OSM server "​https://x.y.y/api/0.6" not only responds to "​https://x.y.y/api/0.6/capabilities" but also
to "​https://x.y.y/api/0/capabilities" or "​https://x.y.y/a/capabilities" with valid capabilities. If we get
valid capabilities with an URL we therefore can't be sure that the base URL is valid API URL.

[Don-vip]

In 7466/josm:

fix #10441 - wrong parsing of changesets list in API URL test task + fix EDT violations

[pnorman]

This is intended:

Note: it fetches a list of changesets instead of the much smaller capabilities because - strangely enough -
an OSM server "​https://x.y.y/api/0.6" not only responds to "​https://x.y.y/api/0.6/capabilities" but also
to "​https://x.y.y/api/0/capabilities" or "​https://x.y.y/a/capabilities" with valid capabilities. If we get
valid capabilities with an URL we therefore can't be sure that the base URL is valid API URL.

This is incorrect - ​http://api.openstreetmap.org/api/0/capabilities returns a 404 error, and the same happens with the rails port runnign locally

[Don-vip]

Exact. It was certainly true when it has been written but must have been fixed since. We could switch to simpler capabilities call, then.

[Don-vip]

In 7473/josm:

see #10441 - send capabilities request instead of changesets request when testing API url