Memory leak in groovy with toString() on instances of mixed in class

memory-leak.groovy

class BarMixin {
}

Date.mixin(BarMixin)

100.times {
  println "#${it + 1}"
  def bar = new Date()
  bar.toString()
  sleep 100
}

println "check heap and see all those instances of Date even after you forced a GC"
sleep 20000