fix HeadLink docblock method declaration hints
Update StringTrim to allow '0' as charlist

Update Zend\Filter\StringTrim to allow '0' as charlist
Add Test for empty charlist in StringTrim
Update StringTrimTest.php
Update StringTrimTest.php

Removed trailing spaces
#6261 - minor CS fixes in `StringTrim`
#6261 - adding missing coverage annotations
#6261 - adding missing group annotation
Merge branch 'hotfix/#6261-string-trim-allows-0-in-charlist'

Close #6261
Merge branch 'cs/#6038-headlink-docblock-optional-params-hinting'

Type-hints as of phpDocumentor/phpDocumentor2#1194

Close #6038
Digit filter should not touch boolean
Early return for int values which are always just digits
Merge branch 'hotfix/#6277-digit-filter-should-ignore-booleans-backport'

Close #6277