Confirm this is an issue with the Python library and not an underlying OpenAI API

• This is an issue with the Python library

Describe the bug

I encountered the problem of usage.prompt_tokens_details=None.
This is the output of response.usage:
CompletionUsage(completion_tokens=57, prompt_tokens=2181, total_tokens=2518, completion_tokens_details=None, prompt_tokens_details=None, reasoning_tokens=280, traffic_type='ON_DEMAND', promptTokensDetails=[{'modality': 'TEXT', 'tokenCount': 2181}], candidatesTokensDetails=[{'modality': 'TEXT', 'tokenCount': 57}])

Docs for Prompting caching: https://platform.openai.com/docs/guides/prompt-caching

Requirements
Caching is available for prompts containing 1024 tokens or more, with cache hits occurring in increments of 128 tokens. Therefore, the number of cached tokens in a request will always fall within the following sequence: 1024, 1152, 1280, 1408, and so on, depending on the prompt's length.
All requests, including those with fewer than 1024 tokens, will display a cached_tokens field of the usage.prompt_tokens_details Response object or Chat object indicating how many of the prompt tokens were a cache hit. For requests under 1024 tokens, cached_tokens will be zero.

"usage": {
  "prompt_tokens": 2006,
  "completion_tokens": 300,
  "total_tokens": 2306,
  "prompt_tokens_details": {
    "cached_tokens": 1920
  },
  "completion_tokens_details": {
    "reasoning_tokens": 0,
    "accepted_prediction_tokens": 0,
    "rejected_prediction_tokens": 0
  }
}

To Reproduce

My openai version is 1.99.6:
completion = client.chat.completions.create( model="gemini-2.5-pro", messages=messages, tools=available_tools, tool_choice="auto", max_tokens=20000, extra_headers={"X-TT-LOGID": ""} )

Code snippets

OS

Linux

Python version

Python 3.11.2

Library version

openai v1.99.6