[ Version ( since = "1.2" ) ]
public void seal ()
Seals the given node, making it immutable to further changes.
In order to be sealed, the this must have a type and value set. The value will be recursively sealed — if the node holds an object, that JSON object will be sealed, etc.
If the `node` is already immutable, this is a no-op.
| this |
the node to seal |