It is required to have ability to change test result contents after test execution.

Generic use case for this functionality:

Some kind of comment field, which can be filled out by a tester after test execution and test log investigation to simplify work of the person, who will fix particular failure of the tested device/implementation identified by the test.

Only data which affects TestResultCache and TestResultTable (test name, status and execution end time) must be immutable to avoid sync problems.

Other test result data can be safely made mutable.
This requires huge efforts, but it can be done gradually.
For this CR it is enough to make test result properties always mutable.