instruction: Create a Kubernetes configuration with ReferenceGrant, PersistentVolumeClaim, ExampleDataSource resources
output: ```dockerfile
  from the
  Gateway API before you can use this mechanism.Data source referencesThe dataSourceRef field behaves almost the same as the dataSource field. If one is
  specified while the other is not, the API server will give both fields the same value. Neither
  field can be changed after creation, and attempting to specify different values for the two
  fields will result in a validation error. Therefore the two fields will always have the same
  contents.There are two differences between the dataSourceRef field and the dataSource field that
  users should be aware of:The dataSource field ignores invalid values (as if the field was blank) while the
  dataSourceRef field never ignores values and will cause an error if an invalid value is
  used. Invalid values are any core object (objects with no apiGroup) except for PVCs.The dataSourceRef field may contain different types of objects, while the dataSource field
  only allows PVCs and VolumeSnapshots.When the CrossNamespaceVolumeDataSource feature is enabled, there are additional differences:The dataSource field only allows local objects, while the dataSourceRef field allows
  objects in any namespaces.When namespace is specified, dataSource and dataSourceRef are not synced.Users should always use dataSourceRef on clusters that have the feature gate enabled, and
  fall back to dataSource on clusters that do not. It is not necessary to look at both fields
  under any circumstance. The duplicated values with slightly different semantics exist only for
  backwards compatibility. In particular, a mixture of older and newer controllers are able to
  interoperate because the fields are the same.Using volume populatorsVolume populators are controllers that can
  create non-empty volumes, where the contents of the volume are determined by a Custom Resource.
  Users create a populated volume by referring to a Custom Resource using the dataSourceRef field:apiVersion: v1
  kind: PersistentVolumeClaim
  metadata:
   name: populated-pvc
  spec:
   dataSourceRef:
   name: example-name
   kind: ExampleDataSource
   apiGroup: example.storage.k8s.io
   accessModes:
   - ReadWriteOnce
   resources:
   requests:
   storage: 10Gi
  Because volume populators are external components, attempts to create a PVC that uses one
  can fail if not all the correct components are installed. External controllers should generate
  events on the PVC to provide feedback on the status of the creation, including warnings if
  the PVC cannot be created due to some missing component.You can install the alpha volume data source validator
  controller into your cluster. That controller generates warning Events on a PVC in the case that no populator
  is registered to handle that kind of data source. When a suitable populator is installed for a PVC, it's the
  responsibility of that populator controller to report Events that relate to volume creation and issues during
  the process.Using a cross-namespace volume data sourceFEATURE STATE:
  Kubernetes v1.26 [alpha]Create a ReferenceGrant to allow the namespace owner to accept the reference.
  You define a populated volume by specifying a cross namespace volume data source
  using the dataSourceRef field. You must already have a valid ReferenceGrant
  in the source namespace:apiVersion: gateway.networking.k8s.io/v1beta1
  kind: ReferenceGrant
  metadata:
   name: allow-ns1-pvc
   namespace: default
  spec:
  ```