SPIGOT-3531: Refactor pathfinder API

src/main/java/org/bukkit/entity/Mob.java

@@ -103,7 +103,7 @@ public interface Mob extends LivingEntity, Lootable {
      *
      * @param predicate a predicate indicating which goals should be removed
      */
-    public void removeGoals(@NotNull Predicate<Goal> predicate);
+    public void removeGoalIf(@NotNull Predicate<Goal> predicate);
 
     /**
      * Disable all goals of a given type.

src/main/java/org/bukkit/entity/ai/CustomGoalDefinition.java

@@ -0,0 +1,73 @@
+package org.bukkit.entity.ai;
+
+import java.util.Set;
+import org.bukkit.NamespacedKey;
+import org.bukkit.entity.Mob;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Custom goal definition.
+ *
+ * <p>In order to add custom goals to mobs, plugins should implement this
+ * interface.
+ *
+ * @see GoalFactory#custom(NamespacedKey, int, CustomGoalDefinition)
+ */
+public interface CustomGoalDefinition {
+
+    /**
+     * Action executed when a mob starts following this goal.
+     *
+     * @param mob a mob which started following this goal
+     */
+    default void start(@NotNull Mob mob) {}
+
+    /**
+     * Action executed when a mob stops following this goal.
+     *
+     * @param mob a mob which stopped following this goal
+     */
+    default void stop(@NotNull Mob mob) {}
+
+    /**
+     * Check requirements needed to start following this goal.
+     *
+     * @param mob a mob which is trying to start following this goal
+     * @return whether the mob can start following this goal
+     */
+    boolean canUse(@NotNull Mob mob);
+
+    /**
+     * Check requirements needed to continue following this goal.
+     *
+     * @param mob a mob which is following this goal
+     * @return whether the mob should continue following this goal
+     */
+    default boolean canContinueToUse(@NotNull Mob mob) {
+        return canUse(mob);
+    }
+
+    /**
+     * Action taken by a mob every tick while it's following this goal.
+     *
+     * @param mob a mob which is following this goal
+     */
+    void tick(@NotNull Mob mob);
+
+    /**
+     * Check whether this goal can be interrupted.
+     *
+     * @return whether this goal can be interrupted
+     */
+    default boolean isInterruptible() {
+        return true;
+    }
+
+    /**
+     * Get types of this goal.
+     *
+     * @return goal types of this goal
+     */
+    @NotNull
+    Set<Goal.Type> getTypes();
+}

src/main/java/org/bukkit/entity/ai/Goal.java

@@ -4,13 +4,14 @@ import static org.bukkit.NamespacedKey.BUKKIT;
 import static org.bukkit.NamespacedKey.minecraft;
 import java.util.Set;
 import org.bukkit.Bukkit;
+import org.bukkit.Keyed;
 import org.bukkit.NamespacedKey;
 import org.jetbrains.annotations.NotNull;
 
 /**
  * Mob AI's goal.
  */
-public interface Goal {
+public interface Goal extends Keyed {
 
     /**
      * Attack target entity with arrows.
@@ -265,24 +266,6 @@ public interface Goal {
      */
     NamespacedKey OTHER = new NamespacedKey(BUKKIT, "other");
 
-    /**
-     * Get goal key.
-     *
-     * <p>Note: some vanilla goals are not supported in the API.
-     * {@link Goal#OTHER} will be returned in such cases.
-     *
-     * @return goal key
-     */
-    @NotNull
-    NamespacedKey getId();
-
-    /**
-     * Set goal id.
-     *
-     * @param id new goal id
-     */
-    void setId(@NotNull NamespacedKey id);
-
     /**
      * Check whether this goal is currently enabled.
      *
@@ -310,7 +293,7 @@ public interface Goal {
      *
      * @return whether this goal is active
      */
-    boolean isRunning();
+    boolean isActive();
 
     /**
      * Get goal types associated with this goal.

src/main/java/org/bukkit/entity/ai/GoalFactory.java

@@ -1,6 +1,5 @@
 package org.bukkit.entity.ai;
 
-import java.util.Set;
 import java.util.function.BiPredicate;
 import java.util.function.BooleanSupplier;
 import java.util.function.Function;
@@ -905,71 +904,9 @@ public interface GoalFactory {
      *
      * @param goalId goal id
      * @param priority goal priority
-     * @param customGoalRegistration goal definition
+     * @param customGoalDefinition goal definition
      * @return created goal
      */
     @NotNull
-    Goal custom(@NotNull NamespacedKey goalId, int priority, @NotNull CustomGoalRegistration customGoalRegistration);
-
-    /**
-     * Custom goal definition.
-     */
-    interface CustomGoalRegistration {
-
-        /**
-         * Action executed when a mob starts following this goal.
-         *
-         * @param mob a mob which started following this goal
-         */
-        default void start(@NotNull Mob mob) {}
-
-        /**
-         * Action executed when a mob stops following this goal.
-         *
-         * @param mob a mob which stopped following this goal
-         */
-        default void stop(@NotNull Mob mob) {}
-
-        /**
-         * Check requirements needed to start following this goal.
-         *
-         * @param mob a mob which is trying to start following this goal
-         * @return whether the mob can start following this goal
-         */
-        boolean canUse(@NotNull Mob mob);
-
-        /**
-         * Check requirements needed to continue following this goal.
-         *
-         * @param mob a mob which is following this goal
-         * @return whether the mob should continue following this goal
-         */
-        default boolean canContinueToUse(@NotNull Mob mob) {
-            return canUse(mob);
-        }
-
-        /**
-         * Action taken by a mob every tick while it's following this goal.
-         *
-         * @param mob a mob which is following this goal
-         */
-        void action(@NotNull Mob mob);
-
-        /**
-         * Check whether this goal can be interrupted.
-         *
-         * @return whether this goal can be interrupted
-         */
-        default boolean isInterruptible() {
-            return true;
-        }
-
-        /**
-         * Get types of this goal.
-         *
-         * @return goal types of this goal
-         */
-        @NotNull
-        Set<Goal.Type> getTypes();
-    }
+    Goal custom(@NotNull NamespacedKey goalId, int priority, @NotNull CustomGoalDefinition customGoalDefinition);
 }