#855: Add Block#getCollisionShape and associated API

By: konsolas <vincentyntang@gmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/util/CraftVoxelShape.java

@@ -0,0 +1,41 @@
+package org.bukkit.craftbukkit.util;
+
+import com.google.common.base.Preconditions;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.List;
+import net.minecraft.world.phys.AxisAlignedBB;
+import net.minecraft.world.phys.shapes.VoxelShape;
+import org.bukkit.util.BoundingBox;
+
+public final class CraftVoxelShape implements org.bukkit.util.VoxelShape {
+
+    private final VoxelShape shape;
+
+    public CraftVoxelShape(VoxelShape shape) {
+        this.shape = shape;
+    }
+
+    @Override
+    public Collection<BoundingBox> getBoundingBoxes() {
+        List<AxisAlignedBB> boxes = shape.d(); // PAIL rename toList
+        List<BoundingBox> craftBoxes = new ArrayList<>(boxes.size());
+        for (AxisAlignedBB aabb : boxes) {
+            craftBoxes.add(new BoundingBox(aabb.minX, aabb.minY, aabb.minZ, aabb.maxX, aabb.maxY, aabb.maxZ));
+        }
+        return craftBoxes;
+    }
+
+    @Override
+    public boolean overlaps(BoundingBox other) {
+        Preconditions.checkArgument(other != null, "Other cannot be null");
+
+        for (BoundingBox box : getBoundingBoxes()) {
+            if (box.overlaps(other)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}