FailFast if Ant version does not support javac-modulepath

build.xml

@@ -171,6 +171,15 @@ the common tasks and can be called on to run the main aspects of all the sub-scr
 	</target>
 	
 	<target name="compile" depends="version, ensureBuildDeps, -unpackLibs, -ensureJdk9" description="Compiles the code.">
+        <fail>
+For compiling with Java9 'modulepath' an Ant version 1.9.7+ or 1.10.0+ is required. 
+Your current version is:
+    ${ant.version}
+            <condition>
+                <not><antversion atleast="1.9.8"/></not>
+            </condition>
+        </fail>
+
 		<!-- ant includes the destination dir on the classpath (and there are good reasons to do this), but that also means
 		 the bleeding edge lombok from the previous build is run, which means if there are bugs in it, you can't compile
 		anymore until you 'ant clean'. That's very much not desired, so we kill the processor, which stops lombok from running.