@Override public void close() throws IOException {
        closed = true;
        awaitInflightOperations();
        client.close();
        resultExecutor.shutdown();
        try {
            if (!resultExecutor.awaitTermination(30, TimeUnit.SECONDS)) {
                throw new IOException("Failed to close client in time");
            }
        } catch (InterruptedException e) {
            Thread.currentThread().interrupt();
        }
    }
Same as {@link #feedMany(InputStream, ResultCallback)}, but without a provided {@link ResultCallback} instance.
@see JsonFeeder#feedMany(InputStream, ResultCallback) for details.
vespa-feed-client-api/src/main/java/ai/vespa/feed/client/JsonFeeder.java