@Override
    public boolean isResponseReady(
            final HttpHost host,
            final CredentialsProvider credentialsProvider,
            final HttpContext context) throws AuthenticationException {

        Args.notNull(host, "Auth host");
        Args.notNull(credentialsProvider, "CredentialsProvider");

        final AuthScope authScope = new AuthScope(host, getRealm(), getName());
        final Credentials credentials = credentialsProvider.getCredentials(
                authScope, context);
        if (credentials instanceof UsernamePasswordCredentials) {
            this.credentials = (UsernamePasswordCredentials) credentials;
            return true;
        }

        if (LOG.isDebugEnabled()) {
            final HttpClientContext clientContext = HttpClientContext.cast(context);
            final String exchangeId = clientContext.getExchangeId();
            LOG.debug("{} No credentials found for auth scope [{}]", exchangeId, authScope);
        }
        this.credentials = null;
        return false;
    }
@deprecated This constructor is deprecated to enforce the use of {@link StandardCharsets#UTF_8} encoding
in compliance with RFC 7616 for HTTP Digest Access Authentication. Use the default constructor {@link #DigestScheme()} instead.

@param charset the {@link Charset} set to be used for encoding credentials. This parameter is ignored as UTF-8 is always used.
httpclient5/src/main/java/org/apache/hc/client5/http/impl/auth/DigestScheme.java