Fix license warnings
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index df3fc9a..2cfa633 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -1,7 +1,8 @@
+#
 # Licensed to the Apache Software Foundation (ASF) under one or more
 # contributor license agreements.  See the NOTICE file distributed with
 # this work for additional information regarding copyright ownership.
-# The ASF licenses this file to You under the Apache License, Version 2.0
+# The ASF licenses this file to you 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
 #
@@ -12,6 +13,7 @@
 # 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.
+#
 name: CI
 
 on:
diff --git a/NOTICE.txt b/NOTICE.txt
index 1824969..9aa3215 100644
--- a/NOTICE.txt
+++ b/NOTICE.txt
@@ -7,3 +7,6 @@
 AsciidocPlugin.scala
 Copyright (c) 2008, 2009, 2010, 2011 Josh Suereth, Steven Blundy, Josh Cough,
 Mark Harrah, Stuart Roebuck, Tony Sloane, Vesa Vilhonen, Jason Zaugg
+
+sbt
+Copyright (c) 2011, Paul Phillips.
diff --git a/log4j-api-scala_2.10/pom.xml b/log4j-api-scala_2.10/pom.xml
index b05db0e..18ef695 100644
--- a/log4j-api-scala_2.10/pom.xml
+++ b/log4j-api-scala_2.10/pom.xml
@@ -1,7 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
diff --git a/log4j-api-scala_2.11/pom.xml b/log4j-api-scala_2.11/pom.xml
index ca9a454..dc182d7 100644
--- a/log4j-api-scala_2.11/pom.xml
+++ b/log4j-api-scala_2.11/pom.xml
@@ -1,7 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
diff --git a/log4j-api-scala_2.12/pom.xml b/log4j-api-scala_2.12/pom.xml
index 2b5afc7..833986a 100644
--- a/log4j-api-scala_2.12/pom.xml
+++ b/log4j-api-scala_2.12/pom.xml
@@ -1,7 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
diff --git a/log4j-api-scala_2.13/pom.xml b/log4j-api-scala_2.13/pom.xml
index b3aae80..af27184 100644
--- a/log4j-api-scala_2.13/pom.xml
+++ b/log4j-api-scala_2.13/pom.xml
@@ -1,7 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
diff --git a/log4j-api-scala_3/pom.xml b/log4j-api-scala_3/pom.xml
index eaa6639..549af8e 100644
--- a/log4j-api-scala_3/pom.xml
+++ b/log4j-api-scala_3/pom.xml
@@ -1,7 +1,21 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to you 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.
+  -->
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
   <modelVersion>4.0.0</modelVersion>
 
   <parent>
diff --git a/pom.xml b/pom.xml
index ab9be8f..b61be90 100644
--- a/pom.xml
+++ b/pom.xml
@@ -23,7 +23,7 @@
     <groupId>org.apache.logging</groupId>
     <artifactId>logging-parent</artifactId>
     <version>10.0.0</version>
-    <relativePath/>
+    <relativePath />
   </parent>
 
   <artifactId>log4j-api-scala-parent</artifactId>
@@ -60,6 +60,7 @@
     <mockito.version>4.11.0</mockito.version>
     <scalatest.version>3.2.10</scalatest.version>
     <scalatestplus.version>3.2.10.0</scalatestplus.version>
+    <spotbugs-annotations.version>4.7.3</spotbugs-annotations.version>
 
     <!-- plugin versions -->
     <!-- Last one that runs on JDK 8 -->
@@ -75,8 +76,8 @@
         <groupId>org.apache.logging.log4j</groupId>
         <artifactId>log4j-bom</artifactId>
         <version>${log4j.version}</version>
-        <scope>import</scope>
         <type>pom</type>
+        <scope>import</scope>
       </dependency>
 
       <dependency>
@@ -121,18 +122,20 @@
         <version>${scalatestplus.version}</version>
       </dependency>
 
+      <dependency>
+        <groupId>com.github.spotbugs</groupId>
+        <artifactId>spotbugs-annotations</artifactId>
+        <version>${spotbugs-annotations.version}</version>
+      </dependency>
+
     </dependencies>
   </dependencyManagement>
 
   <build>
 
-    <sourceDirectory>src/main/scala</sourceDirectory>
-
-    <testSourceDirectory>src/test/scala</testSourceDirectory>
-
     <pluginManagement>
-      <plugins>
 
+      <plugins>
         <plugin>
           <groupId>net.alchim31.maven</groupId>
           <artifactId>scala-maven-plugin</artifactId>
@@ -172,6 +175,10 @@
 
     </plugins>
 
+    <sourceDirectory>src/main/scala</sourceDirectory>
+
+    <testSourceDirectory>src/test/scala</testSourceDirectory>
+
   </build>
 
 </project>
diff --git a/version.sbt b/version.sbt
index b64de7a..59f8e69 100644
--- a/version.sbt
+++ b/version.sbt
@@ -1 +1,17 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to you 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.
+ */
 ThisBuild / version := "13.0.0-SNAPSHOT"