vanilla-trees :
    # Frequencies: NONE, LOWEST, LOW, NORMAL, HIGH or HIGHER
    frequency : HIGH
    # The list of vanilla tree types (separated by a comma)
    # that will be placed on the generated chunk.
    # > Bukkit manages the tree placing as well as it can.
    #   So, I suggest you follow the biome's tree type, such as
    #   TREE for the forest biome or ACACIA to the Savanna biome.
    #   Take a look at the minecraft-biomes property for the list of vanilla biomes.
    # You can write just the tree type or its percentage.
    #  -> single tree:    TREE
    #  -> multiple trees: TREE(75%),BIRCH(25%)
    # 1.12.2 trees: https://helpch.at/docs/1.12.2/org/bukkit/TreeType.html
    # latest trees: https://hub.spigotmc.org/javadocs/bukkit/org/bukkit/TreeType.html
    types : "TREE(65%),BIG_TREE(5%),BIRCH(30%)"