@Override
    @Test
    @DisplayName("Proxied HttpClient adds required headers to the request")
    protected void proxyConfigurationOtherAuthAddsRequiredHeaders() throws Exception {
        // Given
        final HttpClient.Builder builder =
                getHttpClientFactory()
                        .newBuilder()
                        .proxyAddress(new InetSocketAddress("localhost", server.getPort()))
                        .proxyAuthorization("Other kind of auth");
        try (HttpClient client = builder.build()) {
            // When
            try {
                client.sendAsync(client.newHttpRequestBuilder()
                                       .uri(String.format("http://0.0.0.0:%s/not-found", server.getPort()))
                                       .build(), String.class)
                      .get(10L, TimeUnit.SECONDS);
            } catch (ExecutionException e) {
                // HttpProxyHandler raises an exception when the response is not 200 OK.
                assertThat(e.getCause()).isInstanceOf(UnprocessedRequestException.class);
            }
            // Then
            assertThat(server.getLastRequest())
                    .extracting(RecordedRequest::getHeaders)
                    .extracting(Headers::toMultimap)
                    .hasFieldOrPropertyWithValue("Host", ImmutableList.of("0.0.0.0:" + server.getPort()))
                    .hasFieldOrPropertyWithValue("Proxy-Authorization", ImmutableList.of("Other kind of auth"));
        }
    }
Forked the upstream test case and wrapped client.sendAsync() with try-catch.
kubernetes/src/test/java/com/linecorp/armeria/client/kubernetes/ArmeriaHttpClientProxyTest.java