A Spock specification that fails in Java 8 with CGLIB 3.1 but works with CGLIB 3.2

Range.java

public class Range<T extends Number> implements Comparable<Range<T>> {
	private final T minVal;
	private final T maxVal;

	public Range(T minVal, T maxVal) {
		this.minVal = minVal;
		this.maxVal = maxVal;
	}

	@Override
	public int compareTo(Range<T> other) {
		double myLen = maxVal.doubleValue() - minVal.doubleValue();
		double otherLen = other.maxVal.doubleValue() - other.minVal.doubleValue();
		return Double.compare(myLen, otherLen);
	}	
}

RangeSpec.groovy

import spock.lang.Specification

class RangeSpec extends Specification {
    def "compare ranges"() {
        given:
		Range<Integer> range1 = Spy(constructorArgs: [3, 5])
		Range<Integer> range2 = Spy(constructorArgs: [2, 6])
		
        expect:
		range1.compareTo(range2) < 0
    }
}