* pr/16269:
  Use the latest DTD declaration for Checkstyle

Closes gh-16269

* pr/16265:
  Remove explicit types

Closes gh-16265

Closes gh-16033

Closes gh-16229

* gh-16247:
  Update build and setup configuration to use HTTPS

Closes gh-16247

See gh-16247

* gh-16246:
  Polish "Update build and setup configuration to use HTTPS"
  Update build and setup configuration to use HTTPS

Closes gh-16246

See gh-16246

See gh-16246

* gh-16245:
  Polish "Update build and setup configuration to use HTTPS"
  Update build and setup configuration to use HTTPS

Closes gh-16245

See gh-16245

See gh-16245

* gh-16244:
  Polish "Update build and setup configuration to use HTTPS"
  Update build and setup configuration to use HTTPS

Closes gh-16244

See gh-16244

See gh-16244

* gh-16243:
  Polish "Update build and setup configuration to use HTTPS"
  Update build and setup configuration to use HTTPS

Closes gh-16243

See gh-16243

See gh-16243

* pr/16263:
  Add missing "to" in GitHub SUPPORT file

Closes gh-16263

Closes gh-16211

* pr/15982:
  Polish "Fix request factory used with withBasicAuth"
  Fix request factory used with TestRestTemplate withBasicAuth

Fixes gh-15982

This commit updates the behavior of withBasicAuth on TestRestTemplate
by trying to use the same request factory type as the underlying restTemplate.
If creation of a new instance of the configured request factory class fails,
it falls back to the `ClientHttpRequestFactorySupplier`.

See gh-15982

* pr/16250:
  Switch FaviconRequestHandler visibility to package private