Prior to this commit, the `AbstractFileResolvingResource` would
provide a default implementation for `customizeConnection` which only
sets the HTTP request method as "HEAD".
While this is consistent with its usage within that class (in
`exists()`, `contentLength()` or `lastModified()`), this is not opened
for general usage by sub-classes.
`UrlResource` is an example of that, where its `getInputStream()` method
does not call this customization method.
This not only prevents implementations from calling
`customizeConnection` in various cases, but it also misleads developers
as they might think that customizations will be applied automatically.
This commit ensures that `customizeConnection` is called in all relevant
places and that the configuration of the HTTP method is instead done in
each method as it is use case specific.
Fixes gh-28909
0caa2ac696