Add ability to change Biome outside BentoBox Plugin hierarchy (#30).

To achieve this, I implemented 3 request handlers:
1. BiomeDataRequestHandler will return all data about requested biomeId.
2. BiomeListRequestHandler will return a list of all biomes uniqueIds for requested world.
3. ChangeBiomeRequestHandler will try to change biome with requested input data and return boolean status and string reason.

src/main/java/world/bentobox/biomes/BiomesAddon.java

@@ -15,6 +15,9 @@
 import world.bentobox.bentobox.managers.RanksManager;
 import world.bentobox.biomes.commands.admin.AdminCommand;
 import world.bentobox.biomes.commands.user.BiomesCommand;
+import world.bentobox.biomes.handlers.BiomeDataRequestHandler;
+import world.bentobox.biomes.handlers.BiomeListRequestHandler;
+import world.bentobox.biomes.handlers.ChangeBiomeRequestHandler;
 import world.bentobox.biomes.listeners.ChangeOwnerListener;
 import world.bentobox.biomes.config.Settings;
 import world.bentobox.level.Level;
@@ -120,11 +123,14 @@ public void onEnable()
 			this.registerListener(new ChangeOwnerListener(this));
 
 			// Register Flags
-			this.getPlugin().getFlagsManager().registerFlag(BIOMES_WORLD_PROTECTION);
-			this.getPlugin().getFlagsManager().registerFlag(BIOMES_ISLAND_PROTECTION);
+			this.registerFlag(BIOMES_WORLD_PROTECTION);
+			this.registerFlag(BIOMES_ISLAND_PROTECTION);
 
 			// Register Request Handlers
-			//this.registerRequestHandler(YOUR_REQUEST_HANDLER);
+			this.registerRequestHandler(new BiomeDataRequestHandler(this));
+			this.registerRequestHandler(new BiomeListRequestHandler(this));
+
+			this.registerRequestHandler(new ChangeBiomeRequestHandler(this));
 		}
 		else
 		{

src/main/java/world/bentobox/biomes/handlers/BiomeDataRequestHandler.java

@@ -0,0 +1,111 @@
+package world.bentobox.biomes.handlers;
+
+
+import java.util.Collections;
+import java.util.HashMap;
+import java.util.Map;
+
+import world.bentobox.bentobox.api.addons.request.AddonRequestHandler;
+import world.bentobox.biomes.BiomesAddon;
+import world.bentobox.biomes.database.objects.BiomesObject;
+
+
+/**
+ * This handler returns data for requested challenge.
+ */
+public class BiomeDataRequestHandler extends AddonRequestHandler
+{
+
+	/**
+	 * Constructor creates a new BiomeDataRequestHandler instance.
+	 *
+	 * @param addon of type BiomesAddon
+	 */
+	public BiomeDataRequestHandler(BiomesAddon addon)
+	{
+		super("biome-data");
+		this.addon = addon;
+	}
+
+
+	/**
+	 * @param metaData Required meta data.
+	 * @return Map that returns information about biome
+	 * @see AddonRequestHandler#handle(Map<String, Object>)
+	 */
+	@Override
+	public Object handle(Map<String, Object> metaData)
+	{
+		/*
+            What we need in the metaData:
+				0. "biomeId" -> String
+            What we will return:
+				- Empty Map if biome is not given or not found
+				- Map that contains information about given biome:
+					- uniqueId: the same id that was passed to this handler.
+					- world: string that represents world name where biome operates.
+					- biome: string that represents Minecraft Biome name.
+
+			 		- name: String object of display name for biome.
+					- deployed: boolean object of deployment status.
+			 		- description: List of strings that represents biomes description.
+
+			 		- icon: ItemStack object that represents biome.
+			 		- order: Integer object of order number for given biome.
+
+					- cost: Integer that represents biomes change cost.
+			 		- level: Long that represents minimal island level for this biome to work.
+			 		- permissions: Set of strings that represents required permissions.
+         */
+
+		if (metaData == null ||
+			metaData.isEmpty() ||
+			metaData.get("biomeId") == null ||
+			!(metaData.get("biomeId") instanceof String))
+		{
+			return Collections.emptyMap();
+		}
+
+		BiomesObject biome =
+			this.addon.getAddonManager().getBiomeFromString((String) metaData.get("biomeId"));
+
+		Map<String, Object> biomesDataMap;
+
+		if (biome == null)
+		{
+			biomesDataMap = Collections.emptyMap();
+		}
+		else
+		{
+			biomesDataMap = new HashMap<>();
+
+			biomesDataMap.put("uniqueId", biome.getUniqueId());
+			biomesDataMap.put("world", biome.getWorld());
+			biomesDataMap.put("biome", biome.getBiome().name());
+
+			biomesDataMap.put("name", biome.getFriendlyName());
+			biomesDataMap.put("description", biome.getDescription());
+			biomesDataMap.put("deployed", biome.isDeployed());
+
+			biomesDataMap.put("icon", biome.getIcon());
+			biomesDataMap.put("order", biome.getOrder());
+
+			biomesDataMap.put("cost", biome.getRequiredCost());
+			biomesDataMap.put("level", biome.getRequiredLevel());
+			biomesDataMap.put("permissions", biome.getRequiredPermissions());
+		}
+
+		return biomesDataMap;
+	}
+
+
+// ---------------------------------------------------------------------
+// Section: Variables
+// ---------------------------------------------------------------------
+
+
+	/**
+	 * Variable stores biomes addon.
+	 */
+	private BiomesAddon addon;
+}

src/main/java/world/bentobox/biomes/handlers/BiomeListRequestHandler.java

@@ -0,0 +1,72 @@
+package world.bentobox.biomes.handlers;
+
+
+import org.bukkit.Bukkit;
+import java.util.Collections;
+import java.util.Map;
+import java.util.stream.Collectors;
+
+import world.bentobox.bentobox.api.addons.request.AddonRequestHandler;
+import world.bentobox.biomes.BiomesAddon;
+import world.bentobox.biomes.database.objects.BiomesObject;
+
+
+/**
+ * This handler returns all biomes uniqueIDs that is operating in given world.
+ */
+public class BiomeListRequestHandler extends AddonRequestHandler
+{
+	/**
+	 * Constructor creates a new BiomeListRequestHandler instance.
+	 *
+	 * @param addon of type BiomesAddon
+	 */
+	public BiomeListRequestHandler(BiomesAddon addon)
+	{
+		super("biomes-list");
+		this.addon = addon;
+	}
+
+
+	/**
+	 * @param metaData Required meta data.
+	 * @return Set of strings that contains completed challenges.
+	 * @see AddonRequestHandler#handle(Map <String, Object>)
+	 */
+	@Override
+	public Object handle(Map<String, Object> metaData)
+	{
+		/*
+            What we need in the metaData:
+				0. "world-name" -> String
+            What we will return:
+				- List of biomes in given world.
+         */
+
+		if (metaData == null ||
+			metaData.isEmpty() ||
+			metaData.get("world-name") == null ||
+			!(metaData.get("world-name") instanceof String) ||
+			Bukkit.getWorld((String) metaData.get("world-name")) == null)
+		{
+			return Collections.emptyList();
+		}
+
+		// Return list of biomes unique IDs from given world.
+
+		return this.addon.getAddonManager().
+			getBiomes(Bukkit.getWorld((String) metaData.get("world-name"))).
+			stream().map(BiomesObject::getUniqueId).collect(Collectors.toList());
+	}
+
+
+// ---------------------------------------------------------------------
+// Section: Variables
+// ---------------------------------------------------------------------
+
+
+	/**
+	 * Variable stores challenges addon.
+	 */
+	private BiomesAddon addon;
+}

src/main/java/world/bentobox/biomes/handlers/ChangeBiomeRequestHandler.java

@@ -0,0 +1,166 @@
+package world.bentobox.biomes.handlers;
+
+
+import org.bukkit.Bukkit;
+import org.bukkit.World;
+import java.util.HashMap;
+import java.util.Map;
+import java.util.UUID;
+
+import world.bentobox.bentobox.api.addons.request.AddonRequestHandler;
+import world.bentobox.bentobox.api.user.User;
+import world.bentobox.biomes.BiomesAddon;
+import world.bentobox.biomes.config.Settings;
+import world.bentobox.biomes.database.objects.BiomesObject;
+import world.bentobox.biomes.tasks.BiomeUpdateHelper;
+
+
+/**
+ * This Request Handler returns if requested inputdata can be enough to change biome.
+ */
+public class ChangeBiomeRequestHandler extends AddonRequestHandler
+{
+	/**
+	 * Constructor creates a new ChangeBiomeRequestHandler instance.
+	 *
+	 * @param addon of type ChallengesAddon
+	 */
+	public ChangeBiomeRequestHandler(BiomesAddon addon)
+	{
+		super("biome-request-change");
+		this.addon = addon;
+	}
+
+
+	/**
+	 * @param metaData Required meta data.
+	 * @return Set of strings that contains completed challenges.
+	 * @see AddonRequestHandler#handle(Map<String, Object>)
+	 */
+	@Override
+	public Object handle(Map<String, Object> metaData)
+	{
+		/*
+            What we need in the metaData:
+            	0. "player" -> UUID that represents targeted player UUID.
+				1. "world-name" -> String that represents world name where biome must be changed
+				2. "biomeId" -> String that represents biome unique ID.
+			What you can specify more in metaData:
+				0. "updateMode" -> String that represents how biome is necessary to be changed.
+				1. "range" -> Integer that represents range of biome update change.
+				2. "checkRequirements" -> Boolean that represents if requirements must be checked or not. By default it is true.
+				3. "withdraw" -> Boolean that indicates that money will be withdraw from players account. By default it is true.
+            What we will return:
+            	- Map that contains:
+            	  1. key "status" which is boolean that indicate if biome change was successful.
+            	  2. key "reason" which is string that returns errror message.
+         */
+
+
+		Map<String, Object> returnMap = new HashMap<>(2);
+
+		if (metaData == null || metaData.isEmpty())
+		{
+			returnMap.put("status", false);
+			returnMap.put("reason", "Given MetaData map is not defined!");
+		}
+		else if (!metaData.containsKey("world-name") ||
+			!(metaData.get("world-name") instanceof String) ||
+			Bukkit.getWorld((String) metaData.get("world-name")) == null)
+		{
+			returnMap.put("status", false);
+			returnMap.put("reason", "Missing 'world-name' or it is not valid!");
+		}
+		else if (!metaData.containsKey("player") ||
+			!(metaData.get("player") instanceof UUID))
+		{
+			returnMap.put("status", false);
+			returnMap.put("reason", "Missing 'player' or it is not valid!");
+		}
+		else if (!metaData.containsKey("biomeId") ||
+			!(metaData.get("biomeId") instanceof String) ||
+			this.addon.getAddonManager().getBiomeFromString((String) metaData.get("biomeId")) == null)
+		{
+			returnMap.put("status", false);
+			returnMap.put("reason", "Missing 'biomeId' or it is not valid!");
+		}
+		else
+		{
+			World world = Bukkit.getWorld((String) metaData.get("world-name"));
+			UUID player = (UUID) metaData.get("player");
+			BiomesObject biome = this.addon.getAddonManager().
+				getBiomeFromString((String) metaData.get("biomeId"));
+
+			// Get Update Mode.
+
+			Settings.UpdateMode mode = metaData.containsKey("updateMode") &&
+				metaData.get("updateMode") instanceof String &&
+				Settings.UpdateMode.getMode((String) metaData.get("updateMode")) != null ?
+				Settings.UpdateMode.getMode((String) metaData.get("updateMode")) :
+				this.addon.getSettings().getDefaultMode();
+
+			// Get Update Range.
+
+			int range = metaData.containsKey("range") &&
+				metaData.get("range") instanceof Integer ? (int) metaData.get("range") :
+				this.addon.getSettings().getDefaultSize();
+
+			// Get Requirement Checking
+
+			boolean checkRequirements = !metaData.containsKey("checkRequirements") ||
+				!(metaData.get("checkRequirements") instanceof Boolean) ||
+				(boolean) metaData.get("checkRequirements");
+
+			// Get Withdraw value
+
+			boolean withdraw = !metaData.containsKey("withdraw") ||
+				!(metaData.get("withdraw") instanceof Boolean) ||
+				(boolean) metaData.get("withdraw");
+
+			BiomeUpdateHelper helper = new BiomeUpdateHelper(this.addon,
+				User.getInstance(player),
+				User.getInstance(player),
+				biome,
+				world,
+				mode,
+				range,
+				withdraw);
+
+			if (checkRequirements)
+			{
+				if (helper.canChangeBiome())
+				{
+					helper.updateIslandBiome();
+
+					returnMap.put("status", true);
+					returnMap.put("reason", "Biome is updated by checking all requirements!");
+				}
+				else
+				{
+					returnMap.put("status", false);
+					returnMap.put("reason", "Player does not met requirements for biome changing!");
+				}
+			}
+			else
+			{
+				helper.updateIslandBiome();
+
+				returnMap.put("status", true);
+				returnMap.put("reason", "Biome is updated by skipping all requirements!");
+			}
+		}
+
+		return returnMap;
+	}
+
+
+// ---------------------------------------------------------------------
+// Section: Variables
+// ---------------------------------------------------------------------
+
+
+	/**
+	 * Variable stores biomes addon.
+	 */
+	private BiomesAddon addon;
+}