fixed NPE

application/src/main/java/org/thingsboard/server/controller/TelemetryController.java

@@ -87,6 +87,7 @@ import org.thingsboard.server.service.telemetry.TsData;
 
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.LinkedHashMap;
 import java.util.List;
 import java.util.Map;
@@ -888,11 +889,11 @@ public class TelemetryController extends BaseController {
     }
 
     private List<String> toKeysList(String keys) {
-        List<String> keyList = null;
         if (!StringUtils.isEmpty(keys)) {
-            keyList = Arrays.asList(keys.split(","));
+            return Arrays.asList(keys.split(","));
+        } else {
+            return Collections.emptyList();
         }
-        return keyList;
     }
 
     private DeferredResult<ResponseEntity> getImmediateDeferredResult(String message, HttpStatus status) {

application/src/test/java/org/thingsboard/server/controller/TelemetryControllerTest.java

@@ -113,6 +113,13 @@ public class TelemetryControllerTest extends AbstractControllerTest {
         var monthResult = result.get("t").get(0);
         Assert.assertEquals(22L, monthResult.get("value").asLong());
         Assert.assertEquals(middleOfTheInterval, monthResult.get("ts").asLong());
+
+        // get all latest (without keys parameter)
+        ObjectNode allLatest = doGetAsync("/api/plugins/telemetry/DEVICE/" + device.getId() +
+                        "/values/timeseries?startTs={startTs}&endTs={endTs}&agg={agg}&intervalType={intervalType}&timeZone={timeZone}",
+                ObjectNode.class, startTs, endTs, "SUM", "WEEK_ISO", "Europe/Kyiv");
+        Assert.assertNotNull(allLatest);
+        Assert.assertNotNull(allLatest.get("t"));
     }
 
     @Test