Plugin configuration to support multi-licensing scenarios

README.md

@@ -75,6 +75,7 @@ Available in OSS Repository:  https://oss.sonatype.org/content/repositories/snap
 
 __Plugin declaration__
 
+```xml
     <plugin>
         <groupId>com.mycila</groupId>
         <artifactId>license-maven-plugin</artifactId>
@@ -99,6 +100,49 @@ __Plugin declaration__
             </execution>
         </executions>
     </plugin>
+```
+
+__Plugin declaration ([Multi-Licensing](https://en.wikipedia.org/wiki/Multi-licensing))__
+
+If your source code makes use of multi-licensing, then instead of
+a `<header>` or `<inlineHeader>` element in the configuration
+you can use a `<multi>` element.
+
+The `<multi>` element allows you to specify an optional preamble,
+one or more header (or inlineHeader) and separators between them. These
+options are concatenated together to produce a header template.
+
+```xml
+    <plugin>
+        <groupId>com.mycila</groupId>
+        <artifactId>license-maven-plugin</artifactId>
+        <version>X.Y.ga</version>
+        <configuration>
+            <multi>
+                <preamble><![CDATA[This product is dual-licensed under both the GPLv2 and Apache 2.0 License.]]></preamble>
+                <header>GPL-2.txt</header>
+                <separator>======================================================================</separator>
+                <header>com/mycila/maven/plugin/license/templates/APACHE-2.txt</header>
+            </multi>
+            <properties>
+                <owner>Mycila</owner>
+                <email>[email protected]</email>
+            </properties>
+            <excludes>
+                <exclude>**/README</exclude>
+                <exclude>src/test/resources/**</exclude>
+                <exclude>src/main/resources/**</exclude>
+            </excludes>
+        </configuration>
+        <executions>
+            <execution>
+                <goals>
+                    <goal>check</goal>
+                </goals>
+            </execution>
+        </executions>
+    </plugin>
+```
 
 ## Documentation ##
 
@@ -150,7 +194,7 @@ You can find those license templates with preconfigured placeholders [here](http
 
 Properties which can be used as placeholder comes from:
 
- - Environnment variables
+ - Environment variables
  - POM properties
    - `project.groupId`
    - `project.artifactId`

license-maven-plugin/src/main/java/com/mycila/maven/plugin/license/AbstractLicenseMojo.java

@@ -106,6 +106,18 @@ public abstract class AbstractLicenseMojo extends AbstractMojo {
     @Parameter
     public String[] validHeaders = new String[0];
 
+    /**
+     * Alternative to `header`, `inlineHeader`, or `validHeaders`
+     * for use when code is multi-licensed.
+     * Whilst you could create a concatenated header yourself,
+     * a cleaner approach may be to specify more than one header
+     * and have them concatenated together by the plugin. This
+     * allows you to maintain each distinct license header in
+     * its own file and combined them in different ways.
+     */
+    @Parameter
+    public Multi multi;
+
     /**
      * Allows the use of external header definitions files. These files are
      * properties like files.
@@ -321,7 +333,7 @@ public void checkUnknown() throws MojoExecutionException {
     @SuppressWarnings({"unchecked"})
     public final void execute(final Callback callback) throws MojoExecutionException, MojoFailureException {
         if (!skip) {
-            if (header == null && (this.inlineHeader == null || this.inlineHeader.isEmpty())) {
+            if (!hasHeader()) {
                 warn("No header file specified to check for license");
                 return;
             }
@@ -338,7 +350,7 @@ public final void execute(final Callback callback) throws MojoExecutionException
             }
             finder.setPluginClassPath(getClass().getClassLoader());
 
-            final HeaderSource headerSource = HeaderSource.of(this.inlineHeader, this.header, this.encoding, this.finder);
+            final HeaderSource headerSource = HeaderSource.of(this.multi, this.inlineHeader, this.header, this.encoding, this.finder);
             final Header h = new Header(headerSource, headerSections);
             debug("Header: %s", h.getLocation());
 
@@ -347,7 +359,7 @@ public final void execute(final Callback callback) throws MojoExecutionException
             }
             final List<Header> validHeaders = new ArrayList<Header>(this.validHeaders.length);
             for (String validHeader : this.validHeaders) {
-                final HeaderSource validHeaderSource = HeaderSource.of(null, validHeader, this.encoding, this.finder);
+                final HeaderSource validHeaderSource = HeaderSource.of(null, null, validHeader, this.encoding, this.finder);
                 validHeaders.add(new Header(validHeaderSource, headerSections));
             }
 
@@ -455,6 +467,14 @@ public void run() {
         }
     }
 
+    private boolean hasHeader() {
+        return
+                (multi != null
+                        && ((multi.headers != null && multi.headers.length > 0)
+                        || (multi.inlineHeaders != null && multi.inlineHeaders.length > 0 && !multi.inlineHeaders[0].isEmpty()))
+                ) || (header != null || (inlineHeader != null && !this.inlineHeader.isEmpty()));
+    }
+
     private int getNumberOfExecutorThreads() {
         return nThreads > 0 ?
             nThreads :

license-maven-plugin/src/main/java/com/mycila/maven/plugin/license/Multi.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright (C) 2008 Mycila ([email protected])
+ *
+ * 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.mycila.maven.plugin.license;
+
+import org.apache.maven.plugins.annotations.Parameter;
+
+public class Multi {
+
+    public static final String DEFAULT_SEPARATOR =
+            "---------------------------------------------------------------------";
+
+    /**
+     * Preamble text which if present is placed before the first header.
+     */
+    @Parameter
+    String preamble;
+
+    /**
+     * Location of each header. It can be a relative path, absolute path,
+     * classpath resource, any URL. The plugin first check if the name specified
+     * is a relative file, then an absolute file, then in the classpath. If not
+     * found, it tries to construct a URL from the location.
+     */
+    @Parameter(alias = "header")
+    String[] headers;
+
+    /**
+     * Header, as text, directly in pom file. Using a CDATA section is strongly recommended.
+     */
+    @Parameter(alias = "inlineHeader")
+    String[] inlineHeaders;
+
+    /**
+     * One of more separators between the headers.
+     * If there is only one separator it is placed between each header.
+     * If there are multiple separators, then the first separator is placed
+     * between the first and second license, the second separator is placed
+     * between the second and third license, and so on...
+     */
+    @Parameter(alias = "separator")
+    String[] separators;
+
+    public String getPreamble() {
+        return preamble;
+    }
+
+    public void setPreamble(final String preamble) {
+        this.preamble = preamble;
+    }
+
+    public String[] getHeaders() {
+        return headers;
+    }
+
+    public void setHeaders(final String[] headers) {
+        this.headers = headers;
+    }
+
+    public String[] getInlineHeaders() {
+        return inlineHeaders;
+    }
+
+    public void setInlineHeaders(final String[] inlineHeaders) {
+        this.inlineHeaders = inlineHeaders;
+    }
+
+    public String[] getSeparators() {
+        return separators;
+    }
+
+    public void setSeparators(final String[] separators) {
+        this.separators = separators;
+    }
+}