なんか違うものになってしまったけど

gistfile1.groovy

class Buzz implements Comparable<Buzz> {

  private int index

  private Buzz(int index) {
    this.index = index
  }

  def static start(int index) {
    while (!isBuzz(index)) {index++}
    new Buzz(index)
  }

  def static end(int index) {
    new Buzz(index)
  }

  Buzz next() {
    int i = index + 1
    while (!isBuzz(i)) {i++}
    new Buzz(i)
  }

  @Override
  int compareTo(Buzz o) {
    this.index <=> o.index
  }

  @Override
  String toString() {
    String.valueOf(index)
  }

  private static isBuzz(int index) {
    index % 3 != 0 && index % 5 == 0
  }
}
println (Buzz.start(1)..Buzz.end(500))