Add current state of led and button to actuator info

pi4j-spring-boot-starter-sample-app/src/main/java/com/pi4j/spring/boot/sample/app/service/Pi4JService.java

@@ -6,10 +6,12 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.actuate.info.Info;
+import org.springframework.boot.actuate.info.InfoContributor;
 import org.springframework.stereotype.Service;
 
 @Service
-public class Pi4JService {
+public class Pi4JService implements InfoContributor {
 
     private static final Logger logger = LoggerFactory.getLogger(Pi4JService.class);
     private static final int PIN_LED = 22; // PIN 15 = BCM 22
@@ -51,6 +53,12 @@ public Pi4JService(@Autowired Context pi4j) {
         }
     }
 
+    @Override
+    public void contribute(Info.Builder builder) {
+        builder.withDetail("pi4j.status.led", led.state());
+        builder.withDetail("pi4j.status.button", button.state());
+    }
+
     private void handleButtonChange(DigitalStateChangeEvent e) {
         logger.info("Button state changed to {}", e.state());
     }