diff --git a/core/src/main/java/one/profiler/AsyncProfiler.java b/core/src/main/java/one/profiler/AsyncProfiler.java
index 9a1514388c3..d077f49e498 100644
--- a/core/src/main/java/one/profiler/AsyncProfiler.java
+++ b/core/src/main/java/one/profiler/AsyncProfiler.java
@@ -1,17 +1,6 @@
 /*
- * Copyright 2018 Andrei Pangin
- *
- * 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.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package one.profiler;
@@ -283,4 +272,4 @@ private void filterThread(Thread thread, boolean enable) {
     private native String execute0(String command) throws IllegalArgumentException, IllegalStateException, IOException;
 
     private native void filterThread0(Thread thread, boolean enable);
-}
+}
\ No newline at end of file
diff --git a/core/src/main/java/one/profiler/AsyncProfilerMXBean.java b/core/src/main/java/one/profiler/AsyncProfilerMXBean.java
index 90abf830c7a..5210c647b09 100644
--- a/core/src/main/java/one/profiler/AsyncProfilerMXBean.java
+++ b/core/src/main/java/one/profiler/AsyncProfilerMXBean.java
@@ -1,17 +1,6 @@
 /*
- * Copyright 2018 Andrei Pangin
- *
- * 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.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package one.profiler;
@@ -40,4 +29,4 @@ public interface AsyncProfilerMXBean {
     String dumpCollapsed(Counter counter);
     String dumpTraces(int maxTraces);
     String dumpFlat(int maxMethods);
-}
+}
\ No newline at end of file
diff --git a/core/src/main/java/one/profiler/Counter.java b/core/src/main/java/one/profiler/Counter.java
index 489053b7290..0d0ec1160cc 100644
--- a/core/src/main/java/one/profiler/Counter.java
+++ b/core/src/main/java/one/profiler/Counter.java
@@ -1,17 +1,6 @@
 /*
- * Copyright 2018 Andrei Pangin
- *
- * 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.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package one.profiler;
@@ -22,4 +11,4 @@
 public enum Counter {
     SAMPLES,
     TOTAL
-}
+}
\ No newline at end of file
diff --git a/core/src/main/java/one/profiler/Events.java b/core/src/main/java/one/profiler/Events.java
index 1731122c725..677c0e4140f 100644
--- a/core/src/main/java/one/profiler/Events.java
+++ b/core/src/main/java/one/profiler/Events.java
@@ -1,17 +1,6 @@
 /*
- * Copyright 2018 Andrei Pangin
- *
- * 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.
+ * Copyright The async-profiler authors
+ * SPDX-License-Identifier: Apache-2.0
  */
 
 package one.profiler;
@@ -24,5 +13,6 @@ public class Events {
     public static final String ALLOC  = "alloc";
     public static final String LOCK   = "lock";
     public static final String WALL   = "wall";
+    public static final String CTIMER = "ctimer";
     public static final String ITIMER = "itimer";
-}
+}
\ No newline at end of file