Fix/csrf headers

[RadovanTomik]

Negotiator pull request:

Description:

Fixes the use of CSRF headers and adds a CI test for request creation.

Checklist:

Make sure you tick all the boxes bellow if they are true or do not apply:

• I have performed a self review of my code
• My code follows Google Java Code style
• I have made my code as simple as possible
• I have added unit tests and the code coverage has not decreased
• I have updated the documentation in all relevant places

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.50%. Comparing base (e4acfd7) to head (9ebdb37).

Additional details and impacted files

@@            Coverage Diff            @@
##             master     #261   +/-   ##
=========================================
  Coverage     78.50%   78.50%           
  Complexity      894      894           
=========================================
  Files           122      122           
  Lines          2740     2740           
  Branches        155      155           
=========================================
  Hits           2151     2151           
  Misses          490      490           
  Partials         99       99           

Flag	Coverage Δ
unit	78.50% <ø> (ø)

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