Function parse_encrypted_data_node_with_policy_and_backend 

pub fn parse_encrypted_data_node_with_policy_and_backend(
    node: Node<'_, '_>,
    policy: &DecryptionPolicy,
    backend: XmlBackend,
) -> Result<EncryptedData, XmlEncError>

Parse a selected xenc:EncryptedData node with an explicit parser backend.