It's take me few minutes to get how "merge with override" works. 🤔
Actually, when you merge if there is 2 value with same key both are kept in the chained list but only the first one will be returned by the get(), correct ?

That's surprising me but if it works why not. I guess one drawback is that merged context takes probably a bit more memory than necessary.

I didn't test it but reading the code I guess that :

TransportContext ctx1 = TransportContext.of(DUMMY_KEY, "111").with(DUMMY_KEY2, "222");
TransportContext ctx2 = TransportContext.of(DUMMY_KEY, "aaa");
TransportContext ctx1Ctx2 = ctx1.with(ctx2);

TransportContext ctx3 = TransportContext.of(DUMMY_KEY, "aaa").with(DUMMY_KEY2, "222");   
// OR TransportContext ctx3 = TransportContext.of(DUMMY_KEY2, "222").with(DUMMY_KEY, "aaa");  
// not sure about the merge order : this makes me think 
// that maybe a better name would be addFirst() or addLast() (instead of with())
// Just because order seems relevant for equals()

assertEquals(ctx1Ctx2, ctx3); 
// From user point of view, I guess this should be equal, but is it ? 
// reading the code I'm not sure. 

and also if I iterate over ctx1Ctx2 and print all key, I will get DUMMY_KEY twice correct ?

(I maybe totally missed something, sorry I didn't take time to execute code)

and also if I iterate over ctx1Ctx2 and print all key, I will get DUMMY_KEY twice correct ?

Yes, that is correct.

and also if I iterate over ctx1Ctx2 and print all key, I will get DUMMY_KEY twice correct ?

@sbernard31 Now that it is fixed by returning Set with keys.

I looked at this.
The keys set resolve the "twice" error.

But not the "equals" one ? See code comment in code block of #85 (comment).

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 93.15%. Comparing base (ef8b0e2) to head (0d78208).

@@             Coverage Diff              @@
##             master      #85      +/-   ##
============================================
+ Coverage     93.11%   93.15%   +0.03%     
- Complexity     1992     1998       +6     
============================================
  Files           132      132              
  Lines          4505     4513       +8     
  Branches        616      616              
============================================
+ Hits           4195     4204       +9     
  Misses          168      168              
+ Partials        142      141       -1     

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I looked at this. The keys set resolve the "twice" error.
I'm not sure what do you mean.

But not the "equals" one ? See code comment in code block of #85 (comment).

Well, that is true, equals will not be true.

(let me know if I should review this again ?)

(let me know if I should review this again ?)

Yes, please ;)

I'm still a bit confused by the idea that a not used key/value pair should still be stored in memory 😅 (#85 (comment))

Actually, when you merge if there is 2 value with same key both are kept in the chained list but only the first one will be returned by the get(), correct ?
That's surprising me but if it works why not. I guess one drawback is that merged context takes probably a bit more memory than necessary.

But alternative will probably lead to more costly(and complex) way to merge 2 TransportContext, so maybe this is the good way. 🤷

So this looks good to me.

Purpose for TransportContext is to have short living, simple and small object. When we will see that this is not enough then alternative would be to use some HashMap underneath.