AsyncHttpClient: Digest authentication cnonce generated with a non-cryptographic random source

The AsyncHttpClient (AHC) library allows Java applications to easily execute HTTP requests and asynchronously process HTTP responses. Prior to 3.0.12 and 2.16.1, Realm.Builder generates the HTTP Digest client nonce with ThreadLocalRandom rather than a cryptographically secure random source. Digest relies on an unpredictable cnonce to resist chosen-plaintext and credential precomputation attacks, so an observer able to infer generator state can reduce the protection of the authentication exchange. This issue is fixed in versions 3.0.12 and 2.16.1.