Structure Operation outcome

In this example, operation outcome resource is having an structural error during the validation operation.

{
    "resourceType": "OperationOutcome",
    "id": "4e605a23-951c-42fb-b828-89f11686a993",
    "issue":  [
        {
            "severity": "error",
            "code": "structure",
            "diagnostics": "<A structural issue in the content such as wrong namespace, or unable to parse the content completely, or invalid json syntax>"
        }
    ]
}