feat: introduce capability interface

src/main/java/minevalley/chestluck/api/core/Lockable.java

@@ -1,5 +1,6 @@
 package minevalley.chestluck.api.core;
 
+import minevalley.chestluck.api.core.capabilities.Capability;
 import minevalley.core.api.Registrant;
 import org.bukkit.Location;
 import org.jetbrains.annotations.Contract;
@@ -90,7 +91,7 @@ public interface Lockable {
      */
     @Nonnull
     @Contract(pure = true)
-    default <T> Optional<T> as(@Nonnull Class<T> capability) throws IllegalArgumentException {
+    default <T extends Capability> Optional<T> as(@Nonnull Class<T> capability) throws IllegalArgumentException {
         if (capability == null) throw new IllegalArgumentException("Capability class cannot be null");
         return capability.isInstance(this) ? Optional.of(capability.cast(this)) : Optional.empty();
     }

src/main/java/minevalley/chestluck/api/core/capabilities/AutoCloseable.java

@@ -6,7 +6,7 @@
 import javax.annotation.Nonnull;
 
 @SuppressWarnings("unused")
-public interface AutoCloseable {
+public interface AutoCloseable extends Capability{
 
     /**
      * Checks whether the AutoCloseable should automatically close after it has been opened

src/main/java/minevalley/chestluck/api/core/capabilities/AutoOpenable.java

@@ -6,7 +6,7 @@
 import javax.annotation.Nonnull;
 
 @SuppressWarnings("unused")
-public interface AutoOpenable {
+public interface AutoOpenable extends Capability {
 
     /**
      * Checks whether the AutoOpenable will automatically open for registrants.

src/main/java/minevalley/chestluck/api/core/capabilities/Capability.java

@@ -0,0 +1,6 @@
+package minevalley.chestluck.api.core.capabilities;
+
+@SuppressWarnings("unused")
+public interface Capability {
+
+}

src/main/java/minevalley/chestluck/api/core/capabilities/ItemReceiver.java

@@ -6,7 +6,7 @@
 import javax.annotation.Nonnull;
 
 @SuppressWarnings("unused")
-public interface ItemReceiver {
+public interface ItemReceiver extends Capability {
 
     /**
      * Checks whether the ItemReceiver can receive items or not.

src/main/java/minevalley/chestluck/api/core/capabilities/ItemSupplier.java

@@ -6,7 +6,7 @@
 import javax.annotation.Nonnull;
 
 @SuppressWarnings("unused")
-public interface ItemSupplier {
+public interface ItemSupplier extends Capability {
 
     /**
      * Checks whether the ItemReceiver can supply items or not.