SPIGOT-2903: Add Structure API

By: Sander Knauff <sanderknauff@hotmail.com>

paper-server/src/main/java/org/bukkit/craftbukkit/CraftServer.java

@@ -183,6 +183,7 @@ import org.bukkit.craftbukkit.metadata.WorldMetadataStore;
 import org.bukkit.craftbukkit.potion.CraftPotionBrewer;
 import org.bukkit.craftbukkit.scheduler.CraftScheduler;
 import org.bukkit.craftbukkit.scoreboard.CraftScoreboardManager;
+import org.bukkit.craftbukkit.structure.CraftStructureManager;
 import org.bukkit.craftbukkit.tag.CraftBlockTag;
 import org.bukkit.craftbukkit.tag.CraftEntityTag;
 import org.bukkit.craftbukkit.tag.CraftFluidTag;
@@ -238,6 +239,7 @@ import org.bukkit.plugin.messaging.StandardMessenger;
 import org.bukkit.potion.Potion;
 import org.bukkit.potion.PotionEffectType;
 import org.bukkit.scheduler.BukkitWorker;
+import org.bukkit.structure.StructureManager;
 import org.bukkit.util.StringUtil;
 import org.bukkit.util.permissions.DefaultPermissions;
 import org.yaml.snakeyaml.Yaml;
@@ -255,6 +257,7 @@ public final class CraftServer implements Server {
     private final SimpleHelpMap helpMap = new SimpleHelpMap(this);
     private final StandardMessenger messenger = new StandardMessenger();
     private final SimplePluginManager pluginManager = new SimplePluginManager(this, commandMap);
+    private final StructureManager structureManager;
     protected final DedicatedServer console;
     protected final DedicatedPlayerList playerList;
     private final Map<String, World> worlds = new LinkedHashMap<String, World>();
@@ -298,6 +301,7 @@ public final class CraftServer implements Server {
             }
         }));
         this.serverVersion = CraftServer.class.getPackage().getImplementationVersion();
+        this.structureManager = new CraftStructureManager(console.getDefinedStructureManager());
 
         Bukkit.setServer(this);
 
@@ -2199,6 +2203,11 @@ public final class CraftServer implements Server {
         return new ArrayList<>(Lists.transform(nms, (entity) -> entity.getBukkitEntity()));
     }
 
+    @Override
+    public StructureManager getStructureManager() {
+        return structureManager;
+    }
+
     @Deprecated
     @Override
     public UnsafeValues getUnsafe() {