diff --git a/kala-collection/src/main/java/kala/collection/AbstractCollection.java b/kala-collection/src/main/java/kala/collection/AbstractCollection.java
index fff56fbf..842dc284 100644
--- a/kala-collection/src/main/java/kala/collection/AbstractCollection.java
+++ b/kala-collection/src/main/java/kala/collection/AbstractCollection.java
@@ -1,35 +1,50 @@
-package kala.collection;
-
-import kala.annotations.Covariant;
-import kala.collection.base.Iterators;
-
-public abstract class AbstractCollection<@Covariant E> implements Collection<E> {
-
-    @Override
-    public boolean isNotEmpty() {
-        return Collection.super.isNotEmpty();
-    }
-
-    @Override
-    public int hashCode() {
-        return Iterators.hash(iterator());
-    }
-
-    @Override
-    public boolean equals(Object obj) {
-        if (this == obj) {
-            return true;
-        }
-        if (!(obj instanceof AnyCollection<?>)
-                || !(canEqual(obj))
-                || !(((AnyCollection<?>) obj).canEqual(this))) {
-            return false;
-        }
-        return sameElements(((Collection<?>) obj));
-    }
-
-    @Override
-    public String toString() {
-        return joinToString(", ", className() + "[", "]");
-    }
-}
+/*
+ * Copyright 2024 Glavo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package kala.collection;
+
+import kala.annotations.Covariant;
+import kala.collection.base.Iterators;
+
+public abstract class AbstractCollection<@Covariant E> implements Collection<E> {
+
+    @Override
+    public boolean isNotEmpty() {
+        return Collection.super.isNotEmpty();
+    }
+
+    @Override
+    public int hashCode() {
+        return Iterators.hash(iterator());
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof AnyCollection<?>)
+                || !(canEqual(obj))
+                || !(((AnyCollection<?>) obj).canEqual(this))) {
+            return false;
+        }
+        return sameElements(((Collection<?>) obj));
+    }
+
+    @Override
+    public String toString() {
+        return joinToString(", ", className() + "[", "]");
+    }
+}
diff --git a/kala-collection/src/main/java/kala/collection/Collection.java b/kala-collection/src/main/java/kala/collection/Collection.java
index 324d70cb..8f63077d 100644
--- a/kala-collection/src/main/java/kala/collection/Collection.java
+++ b/kala-collection/src/main/java/kala/collection/Collection.java
@@ -1,3 +1,18 @@
+/*
+ * Copyright 2024 Glavo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
 package kala.collection;
 
 import kala.annotations.Covariant;