Examples of how 'null' is less than everything in Groovy.

Null.groovy

println "null < ${Long.MIN_VALUE}: ${null < Long.MIN_VALUE}"
println "null < ${Boolean.FALSE}: ${null < Boolean.FALSE}"
println "false < true: ${false < true}"
println "null < new Object(): ${null < new Object()}"
println "null < null: ${null < null}"
def data = ["1", 2, 3L, null, "foo"]
println data.sort()

output.txt

null < -9223372036854775808: true
null < false: true
false < true: true
null < new Object(): true
null < null: false
[null, 2, 3, 1, foo]