Add maven-source-plugin to generate source jar
diff --git a/pom.xml b/pom.xml
index a5b3020..a087c3e 100644
--- a/pom.xml
+++ b/pom.xml
@@ -124,6 +124,18 @@
           <artifactId>maven-surefire-plugin</artifactId>
           <version>${surefire.plugin.version}</version>
         </plugin>
+        <plugin>
+          <groupId>org.apache.maven.plugins</groupId>
+          <artifactId>maven-source-plugin</artifactId>
+          <executions>
+            <execution>
+              <id>attach-sources</id>
+              <goals>
+                <goal>jar</goal>
+              </goals>
+            </execution>
+          </executions>
+        </plugin>
       </plugins>
     </pluginManagement>
     <plugins>