Basic example of a co-packaged liquid and a syringe, contents only, no packaging described

{
  "resourceType" : "PackagedProductDefinition",
  "id" : "package-with-liquid-and-syringe",
  "contained" : [{
    "resourceType" : "DeviceDefinition",
    "id" : "syringeDevice",
    "classification" : [{
      "type" : {
        "text" : "syringe"
      }
    }]
  },
  {
    "resourceType" : "ManufacturedItemDefinition",
    "id" : "liquidItem",
    "status" : "active",
    "manufacturedDoseForm" : {
      "coding" : [{
        "system" : "http://example.org.uk/fhir/doseform",
        "code" : "solution for injection"
      }]
    }
  }],
  "packageFor" : [{
    "reference" : "MedicinalProductDefinition/ProductThatHasThisPackType"
  }],
  "packaging" : {
    "containedItem" : [{
      "item" : {
        "reference" : {
          "reference" : "#liquidItem"
        }
      },
      "amount" : {
        "value" : 20,
        "unit" : "ml",
        "system" : "http://unitsofmeasure.org",
        "code" : "mL"
      }
    },
    {
      "item" : {
        "reference" : {
          "reference" : "#syringeDevice"
        }
      }
    }]
  }
}