QQ: Why couldn't the projectId alone suffice as the key?

Is there a use case where same projectId would have different credentials or different values for enableTrace ?

We need all three fields to support multiple concurrent connections in a shared JVM:

• Credentials: Different connections to the same project can use different service accounts. Keying by projectId alone would cause them to share the same OTel SDK, violating credential isolation and security.
• enableTrace: One connection might enable tracing while another disables it to avoid costs. We must isolate them to respect the connection-level flags.
  Thus, the combination is necessary to ensure strict security and correct configuration behavior.

I see, makes sense. Thanks for explaining.

The shutdown sequesnce seems to imply that the shutdown hooks are executed in the beginning of the shutdown sequence.

So IIUC, this means the logger would still be active. Did you come across any errors when trying to use a logger here to log error messages?

Yeah, so I did read about it and while it is true that shutdown hooks run at the start of JVM shutdown, Java's LogManager registers its own JVM shutdown hook to clean up resources and close all active logging handlers.

Since the JVM executes registered shutdown hooks in a concurrent and arbitrary order, we cannot guarantee whether our telemetry shutdown hook or the LogManager's shutdown hook will execute first. Therefore, avoiding logging inside shutdown hooks is a defensive best practice in Java to prevent race conditions and unreliable logs during VM termination.