Java Agent Lambda Layer does not work on Java 8 runtime

[NathanielRN]

Description

This caught my attention because of open-telemetry/opentelemetry-lambda#107, which said that the Java Agent Lambda Layer only works on the Java 11 runtime.

This is in contrast to the AWS Public Documentation for the Java Agent Lambda Layer which says the Layer is compatible with both Java 8 and Java 11 runtimes.

Our tests most likely did not catch this because we only test our Sample App on the Java 11 run-time.

I confirmed this by using the AWS SDK Sample App from the OTel Lambda repo and testing it only both Java 8 and Java 11:

The trace from the Java 11 run-time:

The trace from the Java 8 run-time:

The Java 8 runtime does not have the S3 trace which means it is not instrumenting the AWS SDK.

cc @anuraaga

[NathanielRN]

We determined that this is a known limitation. Linked a PR to update our documentation that will automatically close this issue when merged.