Revert "HADOOP-14980. [JDK9] Upgrade maven-javadoc-plugin to 3.0.0-M1. Contributed by liyunzhang."

This reverts commit b59e92551d67e05c34e8b5b90d375c3e106afcd1.

pom.xml

@@ -98,7 +98,7 @@ xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xs
     <maven-assembly-plugin.version>2.4</maven-assembly-plugin.version>
     <maven-dependency-plugin.version>3.0.2</maven-dependency-plugin.version>
     <maven-enforcer-plugin.version>3.0.0-M1</maven-enforcer-plugin.version>
-    <maven-javadoc-plugin.version>3.0.0-M1</maven-javadoc-plugin.version>
+    <maven-javadoc-plugin.version>2.10.4</maven-javadoc-plugin.version>
     <maven-gpg-plugin.version>1.5</maven-gpg-plugin.version>
     <maven-remote-resources-plugin.version>1.5</maven-remote-resources-plugin.version>
     <maven-resources-plugin.version>3.0.1</maven-resources-plugin.version>