public Function<? super HttpService, ? extends HttpService>
    newDecorator(Predicate<? super ServiceRequestContext> filter) {
        requireNonNull(filter, "filter");
        return delegate -> new SimpleDecoratingHttpService(delegate) {
            @Override
            public HttpResponse serve(ServiceRequestContext ctx, HttpRequest req) throws Exception {
                if (filter.test(ctx)) {
                    serviceContexts.add(ctx);
                }
                return delegate.serve(ctx, req);
            }
        };
    }
Creates a new decorator to capture the {@link ServiceRequestContext}s
satisfying the given predicate {@code filter}.
junit5/src/main/java/com/linecorp/armeria/testing/server/ServiceRequestContextCaptor.java