Use Maven enforcer (#789)

* Use Maven enforcer to clearly indicate the need for Java 17 during
build, as the usage of Java 8 on the classpath may lead to confusion.
* Also enforce the same minimum Maven version as used in the Maven
wrapper to ensure both mvn and mvnw create similar output.

pom.xml

@@ -394,6 +394,29 @@
         </testResources>
 
         <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-enforcer-plugin</artifactId>
+                <version>3.4.1</version>
+                <configuration>
+                    <rules>
+                        <requireJavaVersion>
+                            <version>17</version>
+                        </requireJavaVersion>
+                        <requireMavenVersion>
+                            <version>3.9.6</version>
+                        </requireMavenVersion>
+                    </rules>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>enforce</id>
+                        <goals>
+                            <goal>enforce</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
             <plugin>
                 <groupId>org.apache.maven.plugins</groupId>
                 <artifactId>maven-site-plugin</artifactId>