Attach the executions to the declaration of the enforcer plugin.

pom.xml

@@ -884,6 +884,26 @@
 				<groupId>org.apache.maven.plugins</groupId>
 				<artifactId>maven-enforcer-plugin</artifactId>
 				<version>3.0.0-M3</version>
+				<executions>
+					<execution>
+						<id>enforce-files-exist</id>
+						<goals>
+							<goal>enforce</goal>
+						</goals>
+						<configuration>
+							<rules>
+								<requireFilesExist>
+									<files>
+										<file>${project.basedir}/README.md</file>
+										<file>${project.basedir}/LICENSE.md</file>
+										<file>${project.basedir}/CHANGELOG.md</file>
+									</files>
+								</requireFilesExist>
+							</rules>
+							<fail>true</fail>
+						</configuration>
+					</execution>
+				</executions>
 			</plugin>
 			<plugin>
 				<groupId>org.codehaus.mojo</groupId>
@@ -923,30 +943,6 @@
 				</executions>
 			</plugin>
 
-			<plugin>
-				<groupId>org.apache.maven.plugins</groupId>
-				<artifactId>maven-enforcer-plugin</artifactId>
-				<executions>
-					<execution>
-						<id>enforce-files-exist</id>
-						<goals>
-							<goal>enforce</goal>
-						</goals>
-						<configuration>
-							<rules>
-								<requireFilesExist>
-									<files>
-										<file>${project.basedir}/README.md</file>
-										<file>${project.basedir}/LICENSE.md</file>
-										<file>${project.basedir}/CHANGELOG.md</file>
-									</files>
-								</requireFilesExist>
-							</rules>
-							<fail>true</fail>
-						</configuration>
-					</execution>
-				</executions>
-			</plugin>
 
 			<plugin>
 				<groupId>org.codehaus.gmaven</groupId>