def jsonString = """{  "Errors": [],
  "Loans": [ 
    {
      "Applications": [
        {
          "id": 1,
          "name": "test"
        }
      ]
    },
    {
      "Applications": [
        {
          "id": 2,
          "name": "test3"
        },
        {
          "id": 3,
          "name": "test3"
        }
      ]
    }
  ]
}"""

def json = new groovy.json.JsonSlurper().parseText(jsonString)

//To get all loan application by Id
def getApplicationById = {id -> json.Loans.Applications.flatten().find{id == it.id}}
println getApplicationById(3)