HADOOP-15814. Maven 3.3.3 unable to parse pom file. Contributed by Wei-Chiu Chuang.

(cherry picked from commit 2626f46691e1e1ad09967d0931a79b95e308c8b8)

hadoop-project/pom.xml

@@ -1482,7 +1482,9 @@
           <artifactId>maven-javadoc-plugin</artifactId>
           <version>${maven-javadoc-plugin.version}</version>
           <configuration>
-            <additionalOptions>-Xmaxwarns 10000</additionalOptions>
+            <additionalOptions>
+                <additionalOption>-Xmaxwarns 10000</additionalOption>
+            </additionalOptions>
           </configuration>
         </plugin>
         <plugin>