GroovyScript Help - Repeating JSON Attributes Have Specific Value.....some of the time?

Here is the complete script which uses the attached file and asserts the codes 

Please follow the inline comments:

//Script Assertion
def json = new groovy.json.JsonSlurper().parseText(context.response)
def expectedCode = 'SPX'
//find all non empty handling_codes
def hc_list = json.data.'handling_codes'.findAll() 
//List the non empty handling_codes item count
log.info hc_list.size
//Iterate thru each handling_codes, then check the code list contains at least expectedCode
hc_list.each { hc ->
	log.info hc.code
	assert hc.code.any {it == expectedCode} , "$hc does not contain $expectedCode"
}

EDIT:

Use the above script as Script Assertion where you get the response (not separate groovy script test step)

There are some empty handling_codes are there in the data and assuming that you want to ignore them, hence .findAll() used as shown below (line #5 of the script)

def hc_list = json.data.'handling_codes'.findAll()

if you also need to consider them, then change it to

def hc_list = json.data.'handling_codes'