Abstract targeting to a separate interface (#2557)

* Abstract targeting to a separate interface

* Update Agent.java

* Update Agent.java

Author: ImMorpheus

src/main/java/org/spongepowered/api/entity/Interaction.java

@@ -24,6 +24,6 @@
  */
 package org.spongepowered.api.entity;
 
-public interface Interaction extends Entity, Attackable {
+public interface Interaction extends Entity, Attackable, Targeting {
     // TODO Data
 }

src/main/java/org/spongepowered/api/entity/Targeting.java

@@ -0,0 +1,42 @@
+/*
+ * This file is part of SpongeAPI, licensed under the MIT License (MIT).
+ *
+ * Copyright (c) SpongePowered <https://www.spongepowered.org>
+ * Copyright (c) contributors
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+package org.spongepowered.api.entity;
+
+import org.spongepowered.api.data.Keys;
+import org.spongepowered.api.data.value.Value;
+
+import java.util.Optional;
+
+public interface Targeting extends Entity {
+
+    /**
+     * {@link Keys#TARGET_ENTITY}
+     *
+     * @return The targeted entity, if available
+     */
+    default Optional<Value.Mutable<Entity>> targetEntity() {
+        return this.getValue(Keys.TARGET_ENTITY).map(Value::asMutable);
+    }
+}

src/main/java/org/spongepowered/api/entity/living/Agent.java

@@ -27,11 +27,10 @@
 import org.spongepowered.api.data.Keys;
 import org.spongepowered.api.data.type.HandPreference;
 import org.spongepowered.api.data.value.Value;
-import org.spongepowered.api.entity.Entity;
 import org.spongepowered.api.entity.Leashable;
+import org.spongepowered.api.entity.Targeting;
 import org.spongepowered.api.entity.ai.goal.GoalExecutor;
 import org.spongepowered.api.entity.ai.goal.GoalExecutorType;
-import org.spongepowered.api.entity.ai.goal.builtin.creature.target.TargetGoal;
 import org.spongepowered.api.item.inventory.ArmorEquipable;
 
 import java.util.Optional;
@@ -40,17 +39,7 @@
  * An Agent represents a {@link Living} that has AI. In the future Sponge will
  * allow for custom AIs, but for now vanilla behavior can only be disabled.
  */
-public interface Agent extends Living, Leashable, ArmorEquipable {
-
-    /**
-     * {@link Keys#TARGET_ENTITY}
-     *
-     * @return The targeted entity
-     * @see TargetGoal
-     */
-    default Optional<Value.Mutable<Entity>> targetEntity() {
-        return this.getValue(Keys.TARGET_ENTITY).map(Value::asMutable);
-    }
+public interface Agent extends Living, Leashable, Targeting, ArmorEquipable {
 
     /**
      * {@link Keys#IS_AI_ENABLED}