Issue #14482: Replace UnmodifiableCollectionUtil in LocalizedMessage.

[Carbon14-48]

Issue #14482

the exact same pattern as #19695

Pitest's ArgumentPropagationMutator tries to prove that the defensive copy (Arrays.copyOf) is unnecessary, It does this by making the class point directly to the original array we passed in. this is why we add a test that modifies the array after construction and checks the message to killl the mutation

[romani]

we do not allow pure unit testing, all should be by verifyXxxxxx and pitest should completely ingore this method, if not ingnoring, lets create issue on it.

[romani]

see above

[Carbon14-48]

we do not allow pure unit testing, all should be by verifyXxxxxx and pitest should completely ingore this method, if not ingnoring, lets create issue on it.

yessss i have created an issue with all the methods in this and other PRs , hopefully we get a paramter to skip methods they now only have avoidCallTo which works only at class level so all calls to Collections will be skipped which is too broad