Officially propagate GPL downwards to all files

(cherry picked from commit f2ce020da059718e34342c149172944dfd02b775)

worldedit-core/src/main/java/com/sk89q/worldedit/extent/world/BiomeQuirkExtent.java

@@ -0,0 +1,50 @@
+/*
+ * WorldEdit, a Minecraft world manipulation toolkit
+ * Copyright (C) sk89q <http://www.sk89q.com>
+ * Copyright (C) WorldEdit team and contributors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.sk89q.worldedit.extent.world;
+
+import com.sk89q.worldedit.extent.AbstractDelegateExtent;
+import com.sk89q.worldedit.extent.Extent;
+import com.sk89q.worldedit.math.BlockVector3;
+import com.sk89q.worldedit.world.biome.BiomeType;
+
+/**
+ * Handles quirks when placing biomes.
+ */
+public class BiomeQuirkExtent extends AbstractDelegateExtent {
+
+    /**
+     * Create a new instance.
+     *
+     * @param extent the extent
+     */
+    public BiomeQuirkExtent(Extent extent) {
+        super(extent);
+    }
+
+    @Override
+    public boolean setBiome(BlockVector3 position, BiomeType biome) {
+        boolean success = false;
+        if (!fullySupports3DBiomes()) {
+            // Also place at Y = 0 for proper handling
+            success = super.setBiome(position.withY(0), biome);
+        }
+        return super.setBiome(position, biome) || success;
+    }
+}