AsyncConnectionEndpoint ensureValid() {
        final AsyncConnectionEndpoint endpoint = endpointRef.get();
        if (endpoint == null) {
            throw new IllegalStateException("Endpoint not acquired / already released");
        }
        return endpoint;
    }
@deprecated TLS should be configured by the connection manager
httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/InternalHttpAsyncExecRuntime.java