Naturally occurring Cage-traps in Leaf litter alley

Naturally occurring Cage-traps in Minecraft can only be entered via camouflaged iron trapdoor and camoflauged pressure plates. However, you won't be able to find it in any biome, they can only be found in leaf litter alley and savanna. 

The sides of the cage-trap is made of iron bars and the top of stone with obsidian at the corners. The bottom is also made of stone and obsidian, but this time with a block of chiseled quartz in the center.