I am new to the groovy language

I am trying to parse a JSON file using JsonSlurper in a groovy script. How can I access the names of the arrays in the JSON file below? i.e Array1 and Array2? And also so far I have only tried to declare a list using findall, but how do I declare the list without a condition?

```
def input = new JsonSlurper().parse(reader)
def items = input.Order.Items.findAll { item -> item.Valid == "true"}

```

Input:

```
{
  "Order": {
    "Header": {
      "OrderNumber": "ORD60001",
      "Date": "20190218"
    },
    "Array1": [
      {
        "ItemNumber": "10",
        "MaterialNumber": "MT70001",
        "Quantity": 57,
        "Valid": true
      },
      {
        "ItemNumber": "20",
        "MaterialNumber": "MT80001",
        "Quantity": 28,
        "Valid": false
      }
    ],
    "Array2": [
      {
        "ItemNumber": "10",
        "MaterialNumber": "MT70001",
        "Quantity": 57,
        "Valid": true
      },
      {
        "ItemNumber": "20",
        "MaterialNumber": "MT80001",
        "Quantity": 28,
        "Valid": false
      }
    ]
  }
}

```

Expected Output:

```
{
    "Order": {
        "Header": {
            "OrderNumber": "ORD60001",
            "Date": "20190218"
        },
        "Array1": [
            {
                "ItemNumber": "10",
                "MaterialNumber": "MT70001",
                "Quantity": 57,
                "Valid": true
            }
        ],
        "Array2": [
            {
                "ItemNumber": "10",
                "MaterialNumber": "MT70001",
                "Quantity": 57,
                "Valid": true
            }
        ]
    }
}

```