BE: Handle Flux response bodies in MCP tool call results

Author: elvis-cai

api/src/main/java/io/kafbat/ui/service/mcp/McpSpecificationGenerator.java

@@ -93,7 +93,12 @@ private Mono<CallToolResult> toCallResult(Object result) {
   private Mono<CallToolResult> reponseToCallResult(ResponseEntity<?> response) {
     HttpStatusCode statusCode = response.getStatusCode();
     if (statusCode.is2xxSuccessful() || statusCode.is1xxInformational()) {
-      return Mono.just(this.callToolResult(response.getBody()));
+      Object body = response.getBody();
+      // Handle Flux response bodies by collecting them into a list
+      if (body instanceof Flux<?> flux) {
+        return flux.collectList().map(this::callToolResult);
+      }
+      return Mono.just(this.callToolResult(body));
     } else {
       try {
         return Mono.just(toErrorResult(objectMapper.writeValueAsString(response.getBody())));