public AbstractClientContextBuilder<T> preemptiveAuth(final HttpHost host, final AuthScheme authScheme) {
        Args.notNull(host, "HTTP host");
        if (authSchemeMap == null) {
            authSchemeMap = new HashMap<>();
        }
        authSchemeMap.put(RoutingSupport.normalize(host, schemePortResolver), authScheme);
        return this;
    }
Abstract {@link HttpClientContext} builder.

@param <T> The HttpClientContext type or subtype.
@since 5.4
httpclient5/src/main/java/org/apache/hc/client5/http/AbstractClientContextBuilder.java