If the parameter of the tool is empty, after the framework calls the tool, the Flux stream returns empty content

tools code:

public class FunctionCallTools {

    @Tool(name = "getCurrentDateTime", description = "获取当前时间")
    public static String getCurrentDateTime() {

        return String.valueOf(LocalDateTime.now().atZone(LocaleContextHolder.getTimeZone().toZoneId()));
    }
}

Controller interface code:

@RequestMapping("/tools")
public Flux<String> functionCall(@RequestParam(value = "message", defaultValue = "hello, tell me a joke") String message,
                                      HttpServletResponse response) {
        response.setCharacterEncoding("UTF-8");
        return chatClient.prompt(message)
                .tools(new FunctionCallTools())
                .stream()
                .content();
    }

After open browser，I input "http://localhost:9090/chat/tools?message=what the date is today? "，after running，the browser returned empty，why? but if I called a tool with at least one argument，the browser can return and display the result correctly.

the version of spring-ai I used is 1.0.3，only spring-ai-starter-model-openai and spring-ai-autoconfigure-mode-openai have been introduced

Start by reproducing the /chat/tools endpoint with the zero-argument getCurrentDateTime tool, then compare it with a tool that has an argument. Inspect the chatClient.prompt(...).tools(...).stream().content() path and the Flux handling for tool results. Done means the endpoint emits the tool result for empty-parameter tools as well as parameterized tools.