Now that we have Resin, we should have Amber as well.

Resin is a great addition to the game, but with Resin existing in Minecraft, this would also imply that Amber should exist in Minecraft as well. Perhaps some Pale Gardens could be generated with rivers running through them, in which Amber could be found in Suspicious Gravel or Sand. 

Now what to do with Amber is a different question, my first guess would've been some kinda of magic wand/staff that could be used as a new ranged weapon, with a cool down, since Minecraft doesn't have a Mana System like other games comparable to Minecraft that feature such weapons. But I'm sure others could come up with a use for Amber.