config.json

{
    "configurations": [
        {
            "name": "test",
            "policies": [
                {
                    "name": "AM-Set-Headers.xml",
                    "tokens": [
                        {
                            "xpath": "/AssignMessage/Set/Headers/Header[@name='ENV']",
                            "value": "test"
                        }
                    ]
                }
            ],
            "proxies": [
                {
                    "name": "default.xml",
                    "tokens": [
                        {
                            "xpath": "/ProxyEndpoint/HTTPProxyConnection/BasePath",
                            "value": "/v1/mock"
                        }
                    ]
                }
            ],
            "targets": [
                {
                    "name": "default.xml",
                    "tokens": [
                        {
                            "xpath": "/TargetEndpoint/HTTPTargetConnection/URL",
                            "value": "https://mocktarget.apigee.net"
                        }
                    ]
                }
            ]
        },
        {
            "name": "prod",
            "policies": [
                {
                    "name": "AM-Set-Headers.xml",
                    "tokens": [
                        {
                            "xpath": "/AssignMessage/Set/Headers/Header[@name='ENV']",
                            "value": "prod"
                        }
                    ]
                }
            ],
            "proxies": [
                {
                    "name": "default.xml",
                    "tokens": [
                        {
                            "xpath": "/ProxyEndpoint/HTTPProxyConnection/BasePath",
                            "value": "/v1/mock"
                        }
                    ]
                }
            ],
            "targets": [
                {
                    "name": "default.xml",
                    "tokens": [
                        {
                            "xpath": "/TargetEndpoint/HTTPTargetConnection/URL",
                            "value": "https://mocktarget.apigee.net"
                        }
                    ]
                }
            ]
        }
    ]
}