Tell Apache HttpClient 5 to Read JVM Proxy Settings

For the classic Apache HttpClient 5 API, opt the client into system properties when constructing it:

import org.apache.hc.client5.http.impl.classic.CloseableHttpClient;
import org.apache.hc.client5.http.impl.classic.HttpClients;

try (CloseableHttpClient client = HttpClients.custom()
        .useSystemProperties()
        .build()) {
    // Execute the application's HTTP work with this client.
}

Supply the intended startup arguments, such as -Dhttp.proxyHost=203.0.113.10 -Dhttp.proxyPort=8080, using your real endpoint. The HTTP proxy list supplies public candidates when that route is permitted. Include HTTPS and bypass properties for the destinations involved. Setting a JVM property alone cannot establish that this client uses it.

The builder reference identifies the properties considered by its default components. Explicit route planners or other supplied components can change that behavior.

Make requests through this configured instance. A dependency constructing another client needs its own supported factory or proxy input; an unused client beside it changes nothing.

Identify the library and imports in the failed operation. Commons HttpClient 3, Apache HttpClient 4, HttpClient 5 and Java's java.net.http.HttpClient have different configuration interfaces. An old class recipe cannot explain a client that never uses that generation.