def accountPrefix = '265954'
def jsonString = '''[
  {
    "part": 1,
    "set": 265,
    "ifsc": "88977",
    "value": "569954F3365220210621"
  },
  {
    "part": 2,
    "set": 266,
    "ifsc": "88978",
    "value": "965954F3365220210621"
  },
  {
    "part": 3,
    "set": 267,
    "ifsc": "88979",
    "value": "265954F3365220210621"
  }
]'''
def json = new groovy.json.JsonSlurper().parseText(jsonString)
def accountNumber = json.find {it.value.startsWith(accountPrefix)}.value
println "Account Number fetched: ${accountNumber}"
assert '265954F3365220210621' == accountNumber, 'Test failed'