Add init() method to AbstractEvent

src/main/java/org/spongepowered/api/event/AbstractEvent.java

@@ -41,4 +41,14 @@ public CallbackList getCallbacks() {
         return this.callbacks;
     }
 
+    /**
+     * Called once all fields have been set by the generated
+     * constructor in a subclass.
+     *
+     * <p>This method should be used
+     * to initialize any fields that depend on parameters
+     * passed to the constructor.</p>
+     */
+    protected void init() {}
+
 }

src/main/java/org/spongepowered/api/util/event/factory/ClassGenerator.java

@@ -211,6 +211,21 @@ public static boolean hasImplementation(@Nullable Class<?> type, final Method me
         return false;
     }
 
+    public static boolean hasDeclaredMethod(Class<?> type, String name, Class<?>... params) {
+        while (type != null) {
+            try {
+                type.getDeclaredMethod(name, params);
+                return true;
+            } catch (NoSuchMethodException ignored) {
+                // Try the superclass
+            }
+
+            type = type.getSuperclass();
+        }
+
+        return false;
+    }
+
     /**
      * Get the policy regarding how null parameters are handled.
      *
@@ -355,6 +370,12 @@ public byte[] createClass(final Class<?> type, final String name, final Class<?>
                 mv.visitLabel(afterException);
             }
 
+            // super.init();
+            if (hasDeclaredMethod(parentType, "init")) {
+                mv.visitVarInsn(ALOAD, 0);
+                mv.visitMethodInsn(INVOKESPECIAL, Type.getInternalName(parentType), "init", "()V", false);
+            }
+
             mv.visitInsn(RETURN);
             mv.visitMaxs(0, 0);
             mv.visitEnd();