Clarify that link and event don't need to be objects in the API

[bogdandrutu]

Signed-off-by: Bogdan Drutu bogdandrutu@gmail.com

Related issues #1037

[tigrannajaryan]

Sorry, @bogdandrutu I don't understand this PR. I read the PR description but don't understand how the changes in the text help with that.

[bogdandrutu]

@tigrannajaryan the most important change is the removing of "The Link SHOULD be an immutable type." and equivalent for Event.

[arminru]

Should we still say Links (and Events) SHOULD be immutable? This would mean that if they're implemented as objects, those should be immutable, and if implemented simply by accepting their properties directly in the API, they're already implicitly immutable.

[bogdandrutu]

Also implementing as a non-immutable but passing by value or const ref in c++ is correct:

struct Event {
  std::string name;
  Attributes attributes;
};

class Span {
 public:
  virtual void addEvent(const Event& event) = 0;
  virtual void addEvent(Event event) = 0;
};

Both options are valid, even though the Event is not immutable. Also same construction can be applied in golang where passing by value is possible.

Because of this I prefer to not say anything and as everyone complained, we should let the language SIG members decide on what is the language idiomatic way.

[bogdandrutu]

No significant changes were made to this PR in the past 48h, also this PR does not add any new concept or feature, so can be merged.