[reciever/snmp] The receiver doesn't set StartTimestamp

[dmitryax]

Component(s)

receiver/snmp

What happened?

Working on #17983, I found that the snmp receiver doesn't set StartTimestamp on metrics, at least in the tests. Not sure if it's the actual behavior. While gauges with no StartTimestamp may be okay, Sum metrics with no StartTimestamp are not valid.

Collector version

latest

Environment information

Environment

OS: (e.g., "Ubuntu 20.04")
Compiler(if manually compiled): (e.g., "go 14.2")

OpenTelemetry Collector configuration

No response

Log output

No response

Additional context

No response

[github-actions]

Pinging code owners:

• receiver/snmp: @djaglowski @StefanKurek @tamir-michaeli

See Adding Labels via Comments if you do not have permissions to add labels yourself.

[github-actions]

Pinging code owners for receiver/snmp: @djaglowski @StefanKurek @tamir-michaeli. See Adding Labels via Comments if you do not have permissions to add labels yourself.