[metric spec review] Hide unstable exemplar before release

[dyladan]

    Exemplar in the SDK spec is not yet Stable, need to be removed or hidden if the intention is to ship the initial stable JS package https://github.com/open-telemetry/opentelemetry-js/tree/d154066354863e8c682b4aa488d79c7e914bf91c/experimental/packages/opentelemetry-sdk-metrics/src/exemplar.

Originally posted by @reyang in open-telemetry/community#1204 (comment)

[dyladan]

Exemplar in the SDK spec is not yet Stable, need to be removed or hidden if the intention is to ship the initial stable JS package https://github.com/open-telemetry/opentelemetry-js/tree/d154066354863e8c682b4aa488d79c7e914bf91c/experimental/packages/opentelemetry-sdk-metrics/src/exemplar.

Exemplar is not exposed in the SDK as a public interface yet: https://github.com/open-telemetry/opentelemetry-js/blob/main/experimental/packages/opentelemetry-sdk-metrics/src/index.ts.

originally posted by @legendecas

[dyladan]

@legendecas how would one use unstable exemplar functionality in order to test? Is it possible at all?

[legendecas]

@dyladan Exemplars are not surfaced in any public APIs (you can try to remove the whole directory https://github.com/open-telemetry/opentelemetry-js/tree/main/experimental/packages/opentelemetry-sdk-metrics/src/exemplar). So it is not possible to use the unstable exemplar functionality.

[dyladan]

@legendecas I think this can be closed then. Please reopen if you disagree