express instrumentation - span end prematurely for non-middleware instrumentations

[jzhou7-atl]

• This only affects the JavaScript OpenTelemetry library
• This may affect other libraries, but I would like to get opinions here first

Hi, I want to verify if this is a bug or intended behavior of the current instrumentation code.
I notice in the instrumentation code: https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/opentelemetry-instrumentation-express/src/instrumentation.ts#L236-L242

The span is ended right after it is created unless it's a middleware. It does not even measure the sync execution time of the actual handler.

Should it be put after this line to measure the original handle execution time? https://github.com/open-telemetry/opentelemetry-js-contrib/blob/main/plugins/node/opentelemetry-instrumentation-express/src/instrumentation.ts#L285

I ran a few tests, the time measured for 'request handler' is extremely short, only a couple of microseconds.

Much appreciated for looking into this!