Add helper method to get firmware version from OTA cluster

com.zsmartsystems.zigbee/src/main/java/com/zsmartsystems/zigbee/app/otaserver/ZclOtaUpgradeServer.java

@@ -460,6 +460,19 @@ public void run() {
         return false;
     }
 
+    /**
+     * The file version of the running firmware image on the device. The information is available for the server to
+     * query via ZCL read attribute command. The attribute is optional on the client.
+     * <p>
+     * This calls the synchronous method in the cluster, and always performs an update (ie will not use cached data) to
+     * ensure it is updated following any OTA upgrade operation.
+     *
+     * @return the current firmware version on the remote device
+     */
+    public Integer getCurrentFileVersion() {
+        return cluster.getCurrentFileVersion(Long.MAX_VALUE);
+    }
+
     /**
      * Send an updated status on OTA progress to the listeners
      *

com.zsmartsystems.zigbee/src/test/java/com/zsmartsystems/zigbee/app/otaupgrade/ZclOtaUpgradeServerTest.java

@@ -129,6 +129,16 @@ public Future<CommandResult> answer(InvocationOnMock invocation) {
         assertTrue(notifyCommand.getQueryJitter() >= 1 && notifyCommand.getQueryJitter() <= 100);
     }
 
+    @Test
+    public void getCurrentFileVersion() {
+        ZclOtaUpgradeCluster cluster = Mockito.mock(ZclOtaUpgradeCluster.class);
+        Mockito.when(cluster.getCurrentFileVersion(ArgumentMatchers.anyLong())).thenReturn(1234);
+
+        ZclOtaUpgradeServer server = new ZclOtaUpgradeServer();
+        server.appStartup(cluster);
+        assertEquals(Integer.valueOf(1234), server.getCurrentFileVersion());
+    }
+
     @Override
     public void otaStatusUpdate(ZigBeeOtaServerStatus status, int percent) {
         otaStatusCapture.add(status);