added target_firmware_ts timeseries for the firmware

application/src/main/java/org/thingsboard/server/service/firmware/DefaultFirmwareStateService.java

@@ -187,6 +187,7 @@ public class DefaultFirmwareStateService implements FirmwareStateService {
         List<TsKvEntry> telemetry = new ArrayList<>();
         telemetry.add(new BasicTsKvEntry(ts, new StringDataEntry(DataConstants.TARGET_FIRMWARE_TITLE, firmware.getTitle())));
         telemetry.add(new BasicTsKvEntry(ts, new StringDataEntry(DataConstants.TARGET_FIRMWARE_VERSION, firmware.getVersion())));
+        telemetry.add(new BasicTsKvEntry(ts, new LongDataEntry(DataConstants.TARGET_FIRMWARE_TS, ts)));
         telemetry.add(new BasicTsKvEntry(ts, new StringDataEntry(DataConstants.FIRMWARE_STATE, FirmwareUpdateStatus.QUEUED.name())));
 
         telemetryService.saveAndNotify(tenantId, deviceId, telemetry, new FutureCallback<>() {

common/data/src/main/java/org/thingsboard/server/common/data/DataConstants.java

@@ -99,6 +99,7 @@ public class DataConstants {
     public static final String CURRENT_FIRMWARE_VERSION = "cur_fw_version";
     public static final String TARGET_FIRMWARE_TITLE = "target_fw_title";
     public static final String TARGET_FIRMWARE_VERSION = "target_fw_version";
+    public static final String TARGET_FIRMWARE_TS = "target_fw_ts";
     public static final String FIRMWARE_STATE = "fw_state";
 
     //attributes