Data Watcher

A Data Watcher contains a list of data in the form of an index (Integer) associated with a value (Object).

Data Watchers are utilized for manipulating the play_server_entity_metadata packet. For example, you can create a glowing effect on the client side.

You should refer to the Entity Metadata Format to understand how to manipulate the Data Watcher.

Be cautious with the type of the value! It can be a Byte, Float, etc., so you must use the ExprNumberAs to convert the value to the correct type.