[!!!][BUGFIX] Route defaults have to be specified when creating URIs
Currently when creating URIs one can omit route values that are defined
as defaults of the route.
This is not the intended behavior though, because with a lot of routes
in place this leads to the situation where it gets difficult to target
a certain route.
Thus for a route to match the given route values, one should have to
specify all the routing defaults exactly as they are specified by the
route (except for when a route part appears in the uriPattern).
This is a breaking change if you used Router or UriBuilder to create
URIs without specifying all defaults (see #43589 for details).
Besides, all Fluid ViewHelpers that use the UriBuilder now require the
action argument to be specified.