@Override
    public void close() throws IOException {
        client.close();
    }
{@link CloseableHttpClient} implementation backed by {@link CloseableHttpAsyncClient}
acting as a compatibility bridge with the classic APIs based on the standard
{@link java.io.InputStream} / {@link java.io.OutputStream} model.

@since 5.5
httpclient5/src/main/java/org/apache/hc/client5/http/impl/compat/ClassicToAsyncAdaptor.java