BadRequestException - important details missing

[stargazer33]

Enabled logging (by the way: issue 73) and saw this in stdout:

<6> okhttp3.OkHttpClient           <-- 400 https://generativelanguage.googleapis.com/v1beta/openai/chat/completions (40ms)
...       
<6> okhttp3.OkHttpClient           [{
  "error": {
    "code": 400,
    "message": "Invalid JSON payload received. Unknown name \"seed\": Cannot find field.",
    "status": "INVALID_ARGUMENT",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.BadRequest",
        "fieldViolations": [
          {
            "description": "Invalid JSON payload received. Unknown name \"seed\": Cannot find field."
          }
        ]
      }
    ]
  }
}
]
<6> okhttp3.OkHttpClient           <-- END HTTP (431-byte, 243-gzipped-byte body)

well, errors happen, and the details are clear enough.
But in my code - in the com.openai.errors.BadRequestException I see ONLY THIS:

EXPECTED RESULT: BadRequestException should contain "Invalid JSON payload received. Unknown name "seed": Cannot find field.",
probably together with "type.googleapis.com/google.rpc.BadRequest"

This is NOT a minor issue - I should immediately see why the error happens, the "400" does not really help!

Details

    <dependency>
      <groupId>com.openai</groupId>
      <artifactId>openai-java</artifactId>
      <version>3.4.1</version>
    </dependency>

And I am calling this server: https://generativelanguage.googleapis.com/v1beta/openai
Model: gemma-3-12b-it
Here the "OpenAI compatibility" documentation: https://ai.google.dev/gemini-api/docs/openai

[stargazer33]

One more:
(In Java I get just 400, without all the details)

<6> okhttp3.OkHttpClient           <-- 400 https://generativelanguage.googleapis.com/v1beta/openai/chat/completions (50ms)
<6> okhttp3.OkHttpClient           vary: Origin
<6> okhttp3.OkHttpClient           vary: X-Origin
<6> okhttp3.OkHttpClient           vary: Referer
<6> okhttp3.OkHttpClient           content-type: application/json; charset=UTF-8
<6> okhttp3.OkHttpClient           content-encoding: gzip
<6> okhttp3.OkHttpClient           date: Sun, 07 Sep 2025 09:21:11 GMT
<6> okhttp3.OkHttpClient           server: scaffolding on HTTPServer2
<6> okhttp3.OkHttpClient           content-length: 253
<6> okhttp3.OkHttpClient           x-xss-protection: 0
<6> okhttp3.OkHttpClient           x-frame-options: SAMEORIGIN
<6> okhttp3.OkHttpClient           x-content-type-options: nosniff
<6> okhttp3.OkHttpClient           server-timing: gfet4t7; dur=9
<6> okhttp3.OkHttpClient           alt-svc: h3=":443"; ma=2592000,h3-29=":443"; ma=2592000
<6> okhttp3.OkHttpClient           
<6> okhttp3.OkHttpClient           [{
  "error": {
    "code": 400,
    "message": "Invalid JSON payload received. Unknown name \"frequency_penalty\": Cannot find field.",
    "status": "INVALID_ARGUMENT",
    "details": [
      {
        "@type": "type.googleapis.com/google.rpc.BadRequest",
        "fieldViolations": [
          {
            "description": "Invalid JSON payload received. Unknown name \"frequency_penalty\": Cannot find field."
          }
        ]
      }
    ]
  }
}
]
<6> okhttp3.OkHttpClient           <-- END HTTP (457-byte, 253-gzipped-byte body)

[TomerAberbach]

I think this might be an incompatibility with the Google API. The regular OpenAI API returns a single error object, which is what we expect, while the Google API returns an array of error objects, so we fail to parse it.

I'm thinking we can just fall back to including the entire response body in the exception message if we're unable to parse it

[stargazer33]

including the entire response body in the exception message if we're unable to parse it

Great idea!