Invalid unicode output

If I do this:

PrometheusRegistry registry = new PrometheusRegistry();
Counter.builder()
    .name("test_我喜欢茶")
    .labelNames("test")
    .register(registry)
    .labelValues("test_我喜欢茶").inc();
String accept = OpenMetricsTextFormatWriter.CONTENT_TYPE + "; escaping=allow-utf-8";
ExpositionFormats.init().findWriter(accept).write(System.out, registry.scrape(), EscapingScheme.fromAcceptHeader(accept));

I get this:

# TYPE "test_我喜欢茶" counter
{"test_我喜欢茶_total",test="test_我喜欢茶"} 1.0
# EOF

If I remove the non-ascii characters (still UTF-8 allowed), I get the usual output:

# TYPE test counter
test_total{test="test"} 1.0
# EOF

Is this expected?

Start with OpenMetricsTextFormatWriter, ExpositionFormats.init().findWriter(), and EscapingScheme.fromAcceptHeader() from the example, then reproduce the output using the provided Java snippet. Compare the UTF-8 and ASCII cases to determine whether the quoted metric names and JSON-like output are expected; done means the behavior is confirmed or the intended corrected output is established.