Update spec to permit negative observations of native/exponential histograms?

[callumj]

What are you trying to achieve?

The current spec language prevents observations of negative values of Histograms:

The value is expected to be non-negative. This API SHOULD be documented in a way to communicate to users that this value is expected to be non-negative. This API SHOULD NOT validate this value, that is left to implementations of the API.

However, with the introduction of exponential histograms, negative values are supported thanks to the separation of negative and positive buckets and the removal of _sum counters being directly emitted from the application (leaving the backend to deal with these observations).

I am wondering when the spec will update to permit such a behavior?

Additional context.

Original discussion in opentelemetry-java.