Fix system property name

Author: sungshik

README.md

@@ -63,7 +63,7 @@ On all platforms except macOS, the library internally uses the JDK default imple
 
 On macOS, the library internally uses our custom `WatchService` implementation based on macOS's native [file system event streams](https://developer.apple.com/documentation/coreservices/file_system_events?language=objc) (using JNA).
 Generally, it offers better performance than the JDK default implementation (because the latter uses a polling loop to detect changes only once every two seconds).
-To force the library to use the JDK default implementation on macOS, set system property `engineering.swat.watch.impl` to `default`.
+To force the library to use the JDK default implementation on macOS, set system property `engineering.swat.java-watch.mac` to `jdk`.
 
 ## Related work
 

src/main/java/engineering/swat/watch/impl/jdk/JDKPoller.java

@@ -190,20 +190,22 @@ public Watchable newWatchable(Path path) {
         static final Platform CURRENT = current(); // Assumption: the platform doesn't change
 
         private static Platform current() {
-            var key = "engineering.swat.watch.impl";
-            var val = System.getProperty(key);
-            if (val != null) {
-                if (val.equals("mac")) {
-                    return MAC;
-                } else if (val.equals("default")) {
-                    return DEFAULT;
-                } else {
-                    logger.warn("Unexpected value \"{}\" for system property \"{}\". Using value \"default\" instead.", val, key);
-                    return DEFAULT;
+            if (com.sun.jna.Platform.isMac()) {
+                var key = "engineering.swat.java-watch.mac";
+                var val = System.getProperty(key);
+                if (val != null) {
+                    if (val.equals("jna")) {
+                        return MAC;
+                    } else if (val.equals("jdk")) {
+                        return DEFAULT;
+                    } else {
+                        logger.warn("Unexpected value \"{}\" for system property \"{}\". Using value \"jdk\" instead.", val, key);
+                        return DEFAULT;
+                    }
                 }
             }
 
-            return com.sun.jna.Platform.isMac() ? MAC : DEFAULT;
+            return DEFAULT;
         }
 
         static Platform get() {