fix javadoc generation
diff --git a/impl/pom.xml b/impl/pom.xml
index ca83037..8166550 100644
--- a/impl/pom.xml
+++ b/impl/pom.xml
@@ -1135,7 +1135,6 @@
         <plugins>
             <plugin>
                 <artifactId>maven-javadoc-plugin</artifactId>
-                <artifactId>maven-javadoc-plugin</artifactId>
                 <version>3.1.1</version>
                 <configuration>
                     <source>8</source>