HADOOP-14677. mvn clean compile fails. Contributed by Andras Bokor.

(cherry picked from commit 0fd6d0f2d361536b2baf859ddbb082eb2eadcfcf)

hadoop-maven-plugins/pom.xml

@@ -58,6 +58,9 @@
   </dependencies>
   <build>
     <plugins>
+      <plugin>
+        <artifactId>maven-compiler-plugin</artifactId>
+      </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-plugin-plugin</artifactId>
@@ -65,7 +68,7 @@
         <executions>
           <execution>
             <id>default-descriptor</id>
-            <phase>process-classes</phase>
+            <phase>compile</phase>
           </execution>
         </executions>
       </plugin>