Problem With Anonymous Inner Enum

package com.demo

public enum SampleAppIndicatorCodes {
    YES("Y") {
        @Override
        public String getCode() {
            return booleanCode;
        }
    },
    NO("N") {
        @Override
        public String getCode() {
            return booleanCode;
        }
    };

    private String booleanCode = null

    private SampleAppIndicatorCodes(String booleanCode) {
        this.booleanCode = booleanCode
    }
    public abstract String getCode();

    public static SampleAppIndicatorCodes getSourceIndicator(String booleanCode) {
        if ("Y".equalsIgnoreCase(booleanCode)) {
            return YES
        } else if ("L".equalsIgnoreCase(booleanCode)) {
            return NO
        } else {
            throw new IllegalArgumentException("No  Indicator for the code $booleanCode")
        }
   }
}

package com.demo

import spock.lang.Specification

class SampleAppIndicatorCodesSpec extends Specification {

    def 'test accessing YES code'() {
        expect:
        'Y' == SampleAppIndicatorCodes.YES.code
    }
}