Prevent htmlunit from pulling in commons-logging

Update dependency management to exclude commons-logging and add
an enforcer rule to spring-boot-samples to try and prevent unwanted
commons-logging dependencies from sneaking back in again.

Closes gh-7067

spring-boot-samples/pom.xml

@@ -151,6 +151,29 @@
 					</systemPropertyVariables>
 				</configuration>
 			</plugin>
+			<plugin>
+				<groupId>org.apache.maven.plugins</groupId>
+				<artifactId>maven-enforcer-plugin</artifactId>
+				<executions>
+					<execution>
+						<id>enforce-rules</id>
+						<goals>
+							<goal>enforce</goal>
+						</goals>
+						<configuration>
+							<rules>
+								<bannedDependencies>
+									<excludes>
+										<exclude>commons-logging:*:*</exclude>
+									</excludes>
+									<searchTransitive>true</searchTransitive>
+								</bannedDependencies>
+							</rules>
+							<fail>true</fail>
+						</configuration>
+					</execution>
+				</executions>
+			</plugin>
 		</plugins>
 		<pluginManagement>
 			<plugins>