minecraft-src/assets/minecraft/equipment/leather.json

{
  "layers": {
    "horse_body": [
      {
        "dyeable": {
          "color_when_undyed": -6265536
        },
        "texture": "minecraft:leather"
      }
    ],
    "humanoid": [
      {
        "dyeable": {
          "color_when_undyed": -6265536
        },
        "texture": "minecraft:leather"
      },
      {
        "texture": "minecraft:leather_overlay"
      }
    ],
    "humanoid_leggings": [
      {
        "dyeable": {
          "color_when_undyed": -6265536
        },
        "texture": "minecraft:leather"
      },
      {
        "texture": "minecraft:leather_overlay"
      }
    ]
  }
}