Example of how to deserialize json that starts with an array.

JacksonObjectMapperListOfElementsJson.groovy

package com.charter.aesd.activationlogin.edge.service

import com.charter.aesd.hystrix.utils.aws.CommandBuilderFactory
import com.fasterxml.jackson.databind.ObjectMapper
import groovy.json.JsonSlurper
import groovy.transform.ToString

/**
 * Created by rhasija on 1/20/16.
 */
class FooBar {
    static String foo = """
        [
            {
                "name": "rao",
                "last": "4545"
            }
        ]
    """

    static String fooWorks = """
        {"foos" : [
            {
                "name": "rao",
                "last": "4545"
            }
        ]
        }
    """

    public static void main(String[] args) {

        def text = new JsonSlurper().parseText(foo)
        def factory = CommandBuilderFactory.applyDefaults(new ObjectMapper())
//        factory.deserializationConfig.with(Des)
        def fin = factory.readValue(foo, Foo[])
        println(fin)

    }
}

@ToString
class Foo {
    String name
    String last
}

@ToString
class Def {
    List<Foo> foos
}