Make some fields in LogRecord mutable for consistency with Activity.

[Yun-Ting]

Feature Request

Currently, in Activity, there are methods that allowed users to modify the fields. For example: public Activity SetTag(string key, object? value).

I'm proposing to introduce methods that allow some fields in LogRecord to be mutable - for better consistency with Activity. Also, with this, use cases like redaction or fault-injection in Processor or Exporter could be achieved.

Describe the solution you'd like:

Introduce setter methods to FormattedMessage, State, and StateValues.

OpenTelemetry.Logs.LogRecord.SetFormattedMessage(string formattedMessage) -> void
OpenTelemetry.Logs.LogRecord.SetState(object state) -> void
OpenTelemetry.Logs.LogRecord.SetStateValues(System.Collections.Generic.IReadOnlyList<System.Collections.Generic.KeyValuePair<string, object>> stateValues) -> void

Describe alternatives you've considered.

Making the constructor public to provide users the ability to copy/update fields of their liking.
I think the public setters solution above has better encapsulation based on the OOP principles.
And for use cases like redaction or fault-injection, initialization is not mandatory for modifying a LogRecord.

[dpk83]

+1 to this ask. We have a similar requirement where we are able to perform redaction for traces because Activity supports mutability but same isn't possible with logs.

[noblejacob-kubra]

+1 to this ask.
Similar to this we have a requirement to do custom scrubbing in logs to mask or remove sensitive information.
But was not able to implement because of having no provision to update the State/ StateValues/ FormattedMessage.
Can we add this feature so that it will be consistent with Activity.