In Freeplane Scripts, how to deal with special characters in node links to operating system commands

Question

I'm trying to create a link to a shell script in a Node in Freeplane. When I monitor the text in the node node.link.text I get execute_:script.sh%20/home/dir/file.ext

Ok, It works, but when my path has special characters link spaces or ( ), it isn't able to open. I already tried to use URLEncoder from java.net:

filePath='/home/user/Books/Author Name/File (231)/Book - Author.pdf'
urlEncoder = new URLEncoder()
def urlEncode(String s) {
    urlEncoder.encode(s).replace("+", "%20");
}
fileLink = 'execute:_docreader.sh%20-p%20' + page + '%20' + urlEncode(filePath)
createdNode.link.setText(fileLink)

But I couldn't execute any command with files as arguments whose path have special characters. I even tried to put ' or " in the path manually but it didn't work too.

If filePath are without special characters, like /home/user/Books/AuthorName/file.pdf it works fine.

I look into Freeplane wiki and Freeplane API, looked into the examples but havent found any clue about that.