Remove null items from a list in Groovy

Just use minus:

[null, 30, null] - null

here is an answer if you dont want to keep the original list

void testRemove() {
    def list = [null, 30, null]

    list.removeAll([null])

    assertEquals 1, list.size()
    assertEquals 30, list.get(0)
}

in a handy dandy unit test