Fix behavior for simple double values

common/transport/transport-api/src/main/java/org/thingsboard/server/common/transport/adaptor/JsonConverter.java

@@ -229,7 +229,7 @@ public class JsonConverter {
         String valueAsString = value.getAsString();
         KeyValueProto.Builder builder = KeyValueProto.newBuilder().setKey(key);
         var bd = new BigDecimal(valueAsString);
-        if (bd.stripTrailingZeros().scale() <= 0) {
+        if (bd.stripTrailingZeros().scale() <= 0 && !isSimpleDouble(valueAsString)) {
             try {
                 return builder.setType(KeyValueType.LONG_V).setLongV(bd.longValueExact()).build();
             } catch (ArithmeticException e) {
@@ -251,6 +251,10 @@ public class JsonConverter {
 
     }
 
+    private static boolean isSimpleDouble(String valueAsString) {
+        return valueAsString.contains(".") && !valueAsString.contains("E") && !valueAsString.contains("e");
+    }
+
     public static TransportProtos.ToServerRpcRequestMsg convertToServerRpcRequest(JsonElement json, int requestId) throws JsonSyntaxException {
         JsonObject object = json.getAsJsonObject();
         return TransportProtos.ToServerRpcRequestMsg.newBuilder().setRequestId(requestId).setMethodName(object.get("method").getAsString()).setParams(GSON.toJson(object.get("params"))).build();
@@ -260,7 +264,7 @@ public class JsonConverter {
         String valueAsString = value.getAsString();
         String key = valueEntry.getKey();
         var bd = new BigDecimal(valueAsString);
-        if (bd.stripTrailingZeros().scale() <= 0) {
+        if (bd.stripTrailingZeros().scale() <= 0 && !isSimpleDouble(valueAsString)) {
             try {
                 result.add(new LongDataEntry(key, bd.longValueExact()));
             } catch (ArithmeticException e) {

common/transport/transport-api/src/test/java/JsonConverterTest.java

@@ -53,6 +53,12 @@ public class JsonConverterTest {
         Assert.assertEquals(10L, result.get(0).getLongValue().get().longValue());
     }
 
+    @Test
+    public void testParseAsDoubleWithZero() {
+        var result = JsonConverter.convertToTelemetry(JSON_PARSER.parse("{\"meterReadingDelta\": 42.0}"), 0L);
+        Assert.assertEquals(42.0, result.get(0L).get(0).getDoubleValue().get(), 0.0);
+    }
+
     @Test
     public void testParseAsDouble() {
         var result = JsonConverter.convertToTelemetry(JSON_PARSER.parse("{\"meterReadingDelta\": 1.1}"), 0L);