Add ignore option to error msg
diff --git a/pom.xml b/pom.xml
index 9c758c7..4b2392f 100644
--- a/pom.xml
+++ b/pom.xml
@@ -179,6 +179,7 @@
                                         <requireJavaVersion>
                                             <message>
                                                 You must use JDK 9 or newer due to issues with javadoc in older JDKs, for details check https://bugs.java.com/bugdatabase/view_bug.do?bug_id=8206092
+                                                Use -Dignore.javadocjdk to ignore this requirement, if not building javadoc
                                             </message>
                                             <version>9</version>
                                         </requireJavaVersion>