Add asserts for event body fields

[breedx-splk]

I couldn't find a great way (without casting to AnyValueBody) for users to do assertions around LogRecordData bodies, specifically for writing tests involving Events. This seemed like a pretty low-impact way to add some testability.

[codecov]

Codecov Report

Attention: Patch coverage is 95.65217% with 2 lines in your changes missing coverage. Please review.

Project coverage is 90.01%. Comparing base (ee7fd27) to head (16bd9d2).
Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
...metry/sdk/testing/assertj/LogRecordDataAssert.java	95.65%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #6509      +/-   ##
============================================
+ Coverage     89.98%   90.01%   +0.03%     
- Complexity     6314     6353      +39     
============================================
  Files           703      703              
  Lines         19062    19138      +76     
  Branches       1875     1887      +12     
============================================
+ Hits          17152    17228      +76     
  Misses         1333     1333              
  Partials        577      577              

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[breedx-splk]

I hid the formerly public method that used AnyValue. Ready for another look.

[jack-berg]

I think we can make this assertion now.. See how LogMarshaler checks if body instanceof AnyValueBody.

I might be misunderstanding though. Definitely need to be careful to not expose AnyValue as part of the public API until its stable.

[breedx-splk]

We're slightly mixing up two things here....but the point was this assert will ALWAYS fail right now, because the body is always still STRING type.

[jack-berg]

I think its time we stabilized the AnyValue portions of the log API. Opened #6581 to track.

Its strange to have stable APIs asserting the contents of a log record body which are impossible to produce with using an experimental API. As a part of stabilizing we should fix the Body.Type enum, either by including all the possible value types of AnyValue OR by extending it with a single AnyValue type.

[jack-berg]

Just a few nits, but should be able to get it in for Friday's release.