Update VLLM serving example for compatibility with new vLLM release (r…

…ay-project#46697)

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---------

Signed-off-by: akshay-anyscale <[email protected]>

doc/source/serve/doc_code/vllm_openai_example.py

@@ -18,6 +18,7 @@
 )
 from vllm.entrypoints.openai.serving_chat import OpenAIServingChat
 from vllm.entrypoints.openai.serving_engine import LoRAModulePath
+from vllm.utils import FlexibleArgumentParser
 
 logger = logging.getLogger("ray.serve")
 
@@ -94,7 +95,11 @@ def parse_vllm_args(cli_args: Dict[str, str]):
     Currently uses argparse because vLLM doesn't expose Python models for all of the
     config options we want to support.
     """
-    parser = make_arg_parser()
+    arg_parser = FlexibleArgumentParser(
+        description="vLLM OpenAI-Compatible RESTful API server."
+    )
+
+    parser = make_arg_parser(arg_parser)
     arg_strings = []
     for key, value in cli_args.items():
         arg_strings.extend([f"--{key}", str(value)])