在Assertion中获取Response的headers，获取headers中信息，获取body（content）

// get the  headers of the request
def content= messageExchange.getResponseContent()
def headers = messageExchange.getResponseHeaders()
log.info headers

//get the Content-Type of the headers
def contentType= headers["Content-Type"][0]
log.info contentType

log.info content.contains("<error")