The following script:
def a = [ 'a' , 'b' , 'c' , 'd' ] as Set
def c = a.collect { it + it }
println c.getClass ( ).getName ( ) + ": " + c
results in:
Caught: java.lang.ClassCastException: java.util.ArrayList
at kolesa.run(kolesa.groovy:8)
at kolesa.main(kolesa.groovy)
fixed