Adding module version detection.

api/build.gradle

@@ -25,6 +25,11 @@ jar {
     }
 }
 
+tasks.withType(JavaCompile).configureEach {
+    options.compilerArgs += ['--module-path', classpath.asPath]
+    options.javaModuleVersion = project.version.toString()
+}
+
 test {
     useJUnitPlatform()
 }

api/src/main/java/org/applecommander/applesingle/AppleSingle.java

@@ -47,7 +47,20 @@ public class AppleSingle {
 	
 	public static final String VERSION;
 	static {
-		VERSION = AppleSingle.class.getPackage().getImplementationVersion();
+		String version = AppleSingle.class.getPackage().getImplementationVersion();
+		if (version == null && AppleSingle.class.getModule().getDescriptor() != null) {
+			// When run under the Java Module system (JPMS) we need to get it a different way.
+			version = AppleSingle.class.getModule()
+					.getDescriptor()
+					.version()
+					.map(Object::toString)
+					.orElse("Development Build");
+		}
+		// For unit tests, the descriptor (apparently) doesn't exist, so we skip it.
+		if (version == null) {
+			version = "Unit Testing";
+		}
+		VERSION = version;
 	}	
 	
 	private Map<Integer,Consumer<Entry>> entryConsumers = new HashMap<>();