Added MythicMobs integration

eco-api/src/main/java/com/willfp/eco/core/integrations/customentities/CustomEntitiesManager.java

@@ -0,0 +1,40 @@
+package com.willfp.eco.core.integrations.customentities;
+
+import org.jetbrains.annotations.NotNull;
+
+import java.util.HashSet;
+import java.util.Set;
+
+/**
+ * Class to handle custom entity integrations.
+ */
+public final class CustomEntitiesManager {
+    /**
+     * A set of all registered integrations.
+     */
+    private static final Set<CustomEntitiesWrapper> REGISTERED = new HashSet<>();
+
+    /**
+     * Register a new integration.
+     *
+     * @param integration The integration to register.
+     */
+    public static void register(@NotNull final CustomEntitiesWrapper integration) {
+        REGISTERED.add(integration);
+    }
+
+    /**
+     * Register all the custom entities for a specific plugin into eco.
+     *
+     * @see com.willfp.eco.core.entities.Entities
+     */
+    public static void registerAllEntities() {
+        for (CustomEntitiesWrapper wrapper : REGISTERED) {
+            wrapper.registerAllEntities();
+        }
+    }
+
+    private CustomEntitiesManager() {
+        throw new UnsupportedOperationException("This is a utility class and cannot be instantiated");
+    }
+}

eco-api/src/main/java/com/willfp/eco/core/integrations/customentities/CustomEntitiesWrapper.java

@@ -0,0 +1,15 @@
+package com.willfp.eco.core.integrations.customentities;
+
+import com.willfp.eco.core.integrations.Integration;
+
+/**
+ * Wrapper class for custom item integrations.
+ */
+public interface CustomEntitiesWrapper extends Integration {
+    /**
+     * Register all the custom entities for a specific plugin into eco.
+     *
+     * @see com.willfp.eco.core.entities.Entities
+     */
+    void registerAllEntities();
+}