"isbeached" condition

Hiya, im looking to spawn an entity at shipwrecks. However, i only want it to be beached shipwrecks. heres my json file right now: {   "asset_id": "diadogs:cat/robin",   "spawn_conditions": [     {       "condition": {         "type": "minecraft:structure",         "structures": ["minecraft:shipwreck"]       },       "priority": 1     }   ] } 
I see on the wiki it says  "is_beached: (optional, defaults to false) Whether or not the shipwreck is beached." I'm not sure how to apply this though. All help is appreciated!!