Regex Filter Doesn't Work If It Contains A Square Bracket Followed By The Regex Whitespace Character. (4374424)

The following filter does not work as it contains a square closing bracket ']'

  match("]\s" value("MESSAGE"));

If the ']' is removed then the filter will work

Possibly underlying operating system

In regular expressions (Regex) '\s' is the "whitespace character" and that will match a space ( ), tab \t, a carriage return \r, a line feed \n or a form feed \f. 
In order to get the filter to work one of the following two workarounds can be applied.

Workaround 1:
This filters a square closing bracket followed by either a space or a tab or a carriage return or a line feed or a form feed.

match("](( )|\t|\r|\n|\f)" value("MESSAGE"));

Workaround 2:
Use a double backslash instead of a single backslash for the whitespace character.

match("]\\s" value("MESSAGE"));