Phillip Webb 76e075ddd0 Polish "Use request factory to support Basic Authentication"
Reduce the surface area of the public API by making the
`BasicAuthentication` and `BasicAuthenticationClientHttpRequestFactory`
class package private.

This commit also attempts to simplify `TestRestTemplate` by keeping
the `RestTemplateBuilder` and reusing it, rather than needing to deal
only with a `RestTemplate` instance.

See gh-17010
2019-05-31 22:35:36 -07:00
..