Add copyright headers
diff --git a/api/src/main/kotlin/com/google/devtools/ksp/KspExperimental.kt b/api/src/main/kotlin/com/google/devtools/ksp/KspExperimental.kt
index 7e86b86..611ea95 100644
--- a/api/src/main/kotlin/com/google/devtools/ksp/KspExperimental.kt
+++ b/api/src/main/kotlin/com/google/devtools/ksp/KspExperimental.kt
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * 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 com.google.devtools.ksp
 
 @RequiresOptIn(
diff --git a/cmdline-parser-gen/src/main/kotlin/CmdlineParserGenerator.kt b/cmdline-parser-gen/src/main/kotlin/CmdlineParserGenerator.kt
index cb4d2b4..3ab9716 100644
--- a/cmdline-parser-gen/src/main/kotlin/CmdlineParserGenerator.kt
+++ b/cmdline-parser-gen/src/main/kotlin/CmdlineParserGenerator.kt
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * 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.
+ */
+
 import com.google.devtools.ksp.processing.*
 import com.google.devtools.ksp.symbol.*
 import java.io.OutputStream
diff --git a/common-deps/src/main/kotlin/com/google/devtools/ksp/KSPConfig.kt b/common-deps/src/main/kotlin/com/google/devtools/ksp/KSPConfig.kt
index 97fe9a4..0a44dc4 100644
--- a/common-deps/src/main/kotlin/com/google/devtools/ksp/KSPConfig.kt
+++ b/common-deps/src/main/kotlin/com/google/devtools/ksp/KSPConfig.kt
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * 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 com.google.devtools.ksp.processing
 
 import java.io.File
diff --git a/common-util/src/main/kotlin/com/google/devtools/ksp/common/ErrorTypeUtils.kt b/common-util/src/main/kotlin/com/google/devtools/ksp/common/ErrorTypeUtils.kt
index f0f68f6..df8ce88 100644
--- a/common-util/src/main/kotlin/com/google/devtools/ksp/common/ErrorTypeUtils.kt
+++ b/common-util/src/main/kotlin/com/google/devtools/ksp/common/ErrorTypeUtils.kt
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * 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 com.google.devtools.ksp.common
 
 import com.google.devtools.ksp.symbol.KSType
diff --git a/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/secondary/AndroidBuiltInKotlinIT.kt b/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/secondary/AndroidBuiltInKotlinIT.kt
index debbcf4..c091f29 100644
--- a/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/secondary/AndroidBuiltInKotlinIT.kt
+++ b/integration-tests/src/test/kotlin/com/google/devtools/ksp/test/secondary/AndroidBuiltInKotlinIT.kt
@@ -1,3 +1,20 @@
+/*
+ * Copyright 2026 Google LLC
+ * Copyright 2010-2026 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ *
+ * 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 com.google.devtools.ksp.test.secondary
 
 import com.google.devtools.ksp.test.fixtures.TemporaryTestProject