[FEATURE] Client Micrometer metrics/observations

[kdebski85]

Is your feature request related to a problem?

I am using Open Search client in my Java application from org.opensearch.client:opensearch-java:2.25.0 artifact.
My application is instrumented with Micrometer and uses OpenTelemetry bridge to send traces and metrics to a tracing platform.
Currently, Open Search client calls are not show as a new span.

What solution would you like?

I would like Open Search client calls to be instrumented by Micrometer. Observations/metrics should be compatible with OpenTelemetry semantics.
Maybe there should be a separate artifact that would add the instrumentation, so it is optional.

[reta]

@kdebski85 please consult Micrometer documentation how to instrument underlying HTTP client [1], fe in case of Apache HttpClient 5 transport:

 final var transport = ApacheHttpClient5TransportBuilder.builder(hosts)
            .setMapper(new JacksonJsonpMapper())
            .setHttpClientConfigCallback(httpClientBuilder -> {
                return httpClientBuilder.addExecInterceptorAfter(
                    ChainElement.RETRY.name(), "micrometer", 
                          new ObservationExecChainHandler(observationRegistry));
            })
            .build();

[1] https://docs.micrometer.io/micrometer/reference/reference/httpcomponents.html