OpenTelemetry for Spring application

Quick question: when reading the documentation about manually configuring OpenTelemetry, I noticed the following line:

Note that when not using Spring boot, tracing each message handler invocation is not supported due to a limitation.

Could anyone elaborate more on this? Is OpenTelemetry supposed to work for Axon in a legacy Spring application?

I’ve created an OpenTelemetrySpanFactory and configured it with the configurer. Does this imply that traces for event handlers are not working?