Parameters allowed and blocked have two setters - with string and collection and one getter returns collection
In this cause default setter for this properties is setter accepted collection.
And when I try to parametrize this interceptor using <param name="blocked">p1, p2</param> setter for collections is invoked with collection of one string "p1, p2".
My proposition: rename (or remove!) setters and getters for parameters allowed and blocked working with collections.
And change function asCollection(String) to calling TextParseUtil.commaDelimitedStringToSet