Fix issues in yang recompilation

Change-Id: I0efec68481b174e63f6a3ec587726bfaf27cfd84
diff --git a/apps/yms/ut/pom.xml b/apps/yms/ut/pom.xml
index 57af901..a4b25e7 100644
--- a/apps/yms/ut/pom.xml
+++ b/apps/yms/ut/pom.xml
@@ -90,6 +90,31 @@
                     </execution>
                 </executions>
             </plugin>
+
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-clean-plugin</artifactId>
+                <version>3.0.0</version>
+                <executions>
+                    <execution>
+                        <id>onos-yang-plugin-workaround</id>
+                        <!-- yang plugin cannot handle non-clean compilation -->
+                        <phase>initialize</phase>
+                        <goals>
+                            <goal>clean</goal>
+                        </goals>
+                        <configuration>
+                            <excludeDefaultDirectories>true</excludeDefaultDirectories>
+                            <filesets>
+                                <fileset>
+                                    <directory>target/generated-sources</directory>
+                                </fileset>
+                            </filesets>
+                        </configuration>
+                    </execution>
+                </executions>
+            </plugin>
+
         </plugins>
     </build>
 </project>