Make Exporters Shutdown spec-compliant

[srikanthccv]

From https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/trace/sdk.md#shutdown-2

Shuts down the exporter. Called when SDK is shut down. This is an opportunity for exporter to do any cleanup required.

Shutdown should be called only once for each Exporter instance. After the call to Shutdown subsequent calls to Export are not allowed and should return a Failure result.

Shutdown should not block indefinitely (e.g. if it attempts to flush the data and the destination is unavailable). OpenTelemetry client authors can decide if they want to make the shutdown timeout configurable.

[github-actions]

This issue was marked stale due to lack of activity. It will be closed in 30 days.

Is there yet a way to force the jaeger exporter to export all created spans? Something like the flush method in the specification?

Thanks in advance