plugin gives items but they instantly replaces with MysqlInventoryBridge inventory content

So ItemJoin items are getting replaced by MySQLInventoryBridge? If this is true, its something you would have to take up with the developer. I cannot find any API allowing me to hook into the plugin so they might have to add support for ItemJoin.

Yes

Just a thought as I am looking to see how I can add support for this plugin, Have you tried setting the items-delay in the items.yml of ItemJoin higher in seconds? If you were to do that it would be possible to give the items after the MySQLInventoryBridge gives the items.

EDIT: It looks like the code for MySQLInventoryBridge is actual within its self, meaning there is no API to hook into to trigger ItemJoin saying hey MSIB gave the items. (Like AuthMe does). It looks like it is a loop that is set at 20L as seen in the source code on MSIB's GitHub so you will have to increase the items-delay in the items.yml of ItemJoin to compensate for that. Maybe the Author of MSIB will add an API in the future.

A delay will be fine, I can create a sync complete event if you need.

Holy biscuits this is an old ticket, not sure how you even came across it lol.

If you wanted to add a sync complete event that would be amazing, then I could add support for your plugin.--Better yet if you could implement a boolean return method such as isPlayerSync(Player) so that I can check if the player has their sync completed at a given moment. This way I could tie it in with the AuthMe method that I already have as every 10 ticks it simply re-calls the method until the player is authenticated.