Create a Customized World: Generator Settings Syntax

I am creating a minigame plugin in Minecraft 1.8.8, and I am trying to create a world on the server startup.
This world needs to have only one biome in it: Extreme Hills. I have been stumped on this for the past few days, and every time I google it, It gives me results for Custom Chunk Generator. This is not what I want.
I finally figured that I could set the WorldCreator.type(WorldType.CUSTOMIZED), but then I would have to configure the generator settings to set the world to have a fixed-biome (as is possible in a vanilla customized world in Single Player).
However, I have not found any information online for the syntax the the String generator has to be. This is an example of my code:

Code:

WorldCreator wc = new WorldCreator("LavaPit");
wc.environment(Environment.NORMAL);
wc.generateStructures(false);
wc.type(WorldType.CUSTOMIZED);
wc.generatorSettings("Generator here"); // Ive tried things like {fixed-biome:3}
Bukkit.getLogger().info(wc.generatorSettings());
Bukkit.createWorld(wc);

I am not even sure that I have to put the biome's id or name in the fixed-biome property, as there is 0 info online.
I have found this wiki page, that at the end has mildly helpful info: https://minecraft.gamepedia.com/Customized

Btw since I am coding in Minecraft 1.8, they have not yet removed WorldCreator.generatorSettings(). If anyone can tell me what the difference is between WorldCreator.generatorSettings(String) and WorldCreator.generator(String) is for 1.8, that would be very helpful.

Thanks in advanced!

 

I think that .generator() is the ChunkGenerator you can create for your own (custom chunk generator), and .generatorSettings() the arguments for a custom world

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{"coordinateScale":684.412,"heightScale":684.412,"lowerLimitScale":512.0,"upperLimitScale":512.0,"depthNoiseScaleX":200.0,"depthNoiseScaleZ":200.0,"depthNoiseScaleExponent":0.5,"mainNoiseScaleX":80.0,"mainNoiseScaleY":160.0,"mainNoiseScaleZ":80.0,"baseSize":8.5,"stretchY":12.0,"biomeDepthWeight":2.0,"biomeDepthOffset":1.0,"biomeScaleWeight":4.0,"biomeScaleOffset":1.0,"seaLevel":63,"useCaves":true,"useDungeons":true,"dungeonChance":8,"useStrongholds":true,"useVillages":true,"useMineShafts":true,"useTemples":true,"useRavines":true,"useWaterLakes":true,"waterLakeChance":4,"useLavaLakes":true,"lavaLakeChance":80,"useLavaOceans":false,"fixedBiome":-1,"biomeSize":4,"riverSize":4,"dirtSize":33,"dirtCount":10,"dirtMinHeight":0,"dirtMaxHeight":256,"gravelSize":33,"gravelCount":8,"gravelMinHeight":0,"gravelMaxHeight":256,"graniteSize":33,"graniteCount":10,"graniteMinHeight":0,"graniteMaxHeight":80,"dioriteSize":33,"dioriteCount":10,"dioriteMinHeight":0,"dioriteMaxHeight":80,"andesiteSize":33,"andesiteCount":10,"andesiteMinHeight":0,"andesiteMaxHeight":80,"coalSize":17,"coalCount":20,"coalMinHeight":0,"coalMaxHeight":128,"ironSize":9,"ironCount":20,"ironMinHeight":0,"ironMaxHeight":64,"goldSize":9,"goldCount":2,"goldMinHeight":0,"goldMaxHeight":32,"redstoneSize":8,"redstoneCount":8,"redstoneMinHeight":0,"redstoneMaxHeight":16,"diamondSize":8,"diamondCount":1,"diamondMinHeight":0,"diamondMaxHeight":16,"lapisSize":7,"lapisCount":1,"lapisCenterHeight":16,"lapisSpread":16}

this is the argument for amplified