Support customized connection id generator

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 57.14286% with 3 lines in your changes missing coverage. Please review.

Project coverage is 95.30%. Comparing base (7f25fc8) to head (76ba349).

Files	Patch %	Lines
src/endpoint.rs	0.00%	3 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## develop #326 +/- ## =========================================== - Coverage 95.30% 95.30% -0.01% =========================================== Files 50 50 Lines 33603 33599 -4 =========================================== - Hits 32027 32023 -4 Misses 1576 1576 ```

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