feat: add ban duplicate classes rule (#126)

* feat: add ban duplicate classes rule

* feat: add extra enforcer dep

Author: stephaniewang526

pom.xml

@@ -101,6 +101,13 @@
           <groupId>org.apache.maven.plugins</groupId>
           <artifactId>maven-enforcer-plugin</artifactId>
           <version>3.0.0-M3</version>
+          <dependencies>
+            <dependency>
+              <groupId>org.codehaus.mojo</groupId>
+              <artifactId>extra-enforcer-rules</artifactId>
+              <version>1.2</version>
+            </dependency>
+          </dependencies>
         </plugin>
         <plugin>
           <groupId>org.codehaus.mojo</groupId>
@@ -259,6 +266,14 @@
                   <version>[1.7,)</version>
                 </requireJavaVersion>
                 <requireUpperBoundDeps/>
+                <banDuplicateClasses>
+                  <scopes>
+                    <scope>compile</scope>
+                    <scope>provided</scope>
+                  </scopes>
+                  <findAllDuplicates>true</findAllDuplicates>
+                  <ignoreWhenIdentical>true</ignoreWhenIdentical>
+                </banDuplicateClasses>
               </rules>
             </configuration>
           </execution>