feat: support user-defined headers

[yndu13]

You need to complete

• [x] unit tests and/or feature tests
• [x] documentation is changed or added

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 95.93%. Comparing base (5efcb38) to head (2288791). Report is 1 commits behind head on master.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #526 +/- ## ========================================== + Coverage 95.90% 95.93% +0.03% ========================================== Files 45 45 Lines 1903 1918 +15 Branches 262 276 +14 ========================================== + Hits 1825 1840 +15 Misses 56 56 Partials 22 22 ```

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