Fix for removing usage in every stream chunk response.

[Hritik003]

Describe the change

This PR fixes an issue where the usage field is always present in streamed completion responses, even when stream_options.include_usage is explicitly set to false.

By changing the Usage field in CompletionResponse to a pointer and tagging it with omitempty, we ensure that if usage is not included in the actual API response, it will be omitted from the parsed Go struct as well.

This improves correctness and reduces confusion when users want to opt out of usage metadata in streaming mode.

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Provide OpenAI documentation link

API Reference: https://platform.openai.com/docs/api-reference/completions/create

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Describe your solution

Modified the CompletionResponse struct to update the Usage field:

Usage *Usage `json:"usage,omitempty"`

This allows Go’s encoding/json to omit the field when it's not present in the streamed response. This makes the client-side response cleaner and honors the behavior expected when include_usage is set to false.

No new libraries or dependencies were added.

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Tests

• Manually tested by calling /v1/completions with both stream_options.include_usage: true and false

• Verified that:

  • When include_usage: true, the field is present.
  • When include_usage: false, the field is omitted in streamed chunks.

• Updated integration tests to assert presence/absence of Usage field conditionally based on stream option.

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Additional context

This PR improves alignment with OpenAI’s API behavior and helps consumers avoid parsing unnecessary fields.

Issue: #1021

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 85.83%. Comparing base (a931bf7) to head (a88015f).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master    #1022   +/-   ##
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  Coverage   85.83%   85.83%           
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  Files          43       43           
  Lines        2316     2316           
=======================================
  Hits         1988     1988           
  Misses        305      305           
  Partials       23       23           

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[Hritik003]

@sashabaranov can you please look into this?

[Hritik003]

@sashabaranov A reminder to look into this?

[sashabaranov]

Thank you!