Prevent ConcurrentModificationExceptions with Mojarra and Java 9+

[larsgrefer]

...when using destruction callbacks on view-scoped beans.

fixes #509

[codecov]

Codecov Report

Merging #511 into master will increase coverage by 0.02%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #511      +/-   ##
============================================
+ Coverage     92.56%   92.58%   +0.02%     
  Complexity      366      366              
============================================
  Files            61       61              
  Lines           955      958       +3     
  Branches        110      111       +1     
============================================
+ Hits            884      887       +3     
  Misses           53       53              
  Partials         18       18

Impacted Files	Coverage Δ	Complexity Δ
...g/joinfaces/autoconfigure/viewscope/ViewScope.java	98.66% <100%> (+0.05%)	15 <2> (ø)	⬇️

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