get Source
Gets the source of this primed TNT. The source is the entity responsible for the creation of this primed TNT. (I.E. player ignites TNT with flint and steel.) Take note that this can be null if there is no suitable source. (created by the spawn method, for example.)
The source will become null if the chunk this primed TNT is in is unloaded then reloaded. If the source Entity becomes invalidated for any reason, such being removed from the world, the returned value will be null.
Return
the source of this primed TNT