Cyclomatic complexity weirdness

Cyclomatic complexity exceeds 20

package com.netflix.asgard

import spock.lang.Specification
import spock.lang.Unroll

@Unroll
class StylerSpec extends Specification {

    void 'availability zone to style class'() {
        expect:
        Styler.availabilityZoneToStyleClass(zone) == styledClass

        where:
        zone              || styledClass
        'us-east-1a'      || 'zoneA'
        'us-east-1b'      || 'zoneB'
        'us-east-1c'      || 'zoneC'
        'us-east-1d'      || 'zoneD'
        'us-west-1a'      || 'zoneA'
        'us-west-1b'      || 'zoneB'
        'us-west-1c'      || 'zoneC'
        'eu-west-1a'      || 'zoneA'
        'eu-west-1b'      || 'zoneB'
        'eu-west-1c'      || 'zoneC'
        'ap-southeast-1a' || 'zoneA'
        'ap-southeast-1b' || 'zoneB'
        'ap-southeast-1c' || 'zoneC'
        'ap-northeast-1a' || 'zoneA'
        'ap-northeast-1b' || 'zoneB'
        'ap-northeast-1c' || 'zoneC'
        null              || null
        ''                || null
        'hello'           || null
        'us-east-1A'      || null
    }
}

No complexity

package com.netflix.asgard

import spock.lang.Specification
import spock.lang.Unroll

@Unroll
class StylerSpec extends Specification {

    void 'availability zone to style class'() {
        expect:
        Styler.availabilityZoneToStyleClass(zone) == styledClass

        where:
        zone              || styledClass
        'us-east-1a'      || 'zoneA'
        'us-east-1b'      || 'zoneB'
        'us-east-1c'      || 'zoneC'
        'us-east-1d'      || 'zoneD'
        'us-west-1a'      || 'zoneA'
        'us-west-1b'      || 'zoneB'
        'us-west-1c'      || 'zoneC'
        'eu-west-1a'      || 'zoneA'
        'eu-west-1b'      || 'zoneB'
        'eu-west-1c'      || 'zoneC'
        'ap-southeast-1a' || 'zoneA'
        'ap-southeast-1b' || 'zoneB'
        'ap-southeast-1c' || 'zoneC'
        'ap-northeast-1a' || 'zoneA'
        'ap-northeast-1b' || 'zoneB'
        'ap-northeast-1c' || 'zoneC'
    }

    void 'availability zone returns null'() {
        expect:
        Styler.availabilityZoneToStyleClass(zone) == null

        where:
        zone         || _
        null         || _
        ''           || _
        'hello'      || _
        'us-east-1A' || _
    }

}