domoticz use "" for no-uom (https://github.com/emsesp/EMS-ESP32/issues/2177#issuecomment-2462320401)

src/mqtt.cpp

@@ -1140,9 +1140,12 @@ void Mqtt::add_ha_uom(JsonObject doc, const uint8_t type, const uint8_t uom, con
         } else if (uom == DeviceValueUOM::SECONDS) {
             doc[uom_ha] = "s";
         } else if (uom != DeviceValueUOM::NONE) {
+            // Domoticz use "" for a no-uom
+            if (discovery_type() == discoveryType::HOMEASSISTANT) {
                 doc[uom_ha] = EMSdevice::uom_to_string(uom); // default
             } 
         }
+    }
 
     // set state and device class
     // also icon, when there is no device class that sets one