toJson method
Implementation
Map<String, dynamic> toJson() => {
if (promptTokens != null) 'prompt_tokens': promptTokens,
if (completionTokens != null) 'completion_tokens': completionTokens,
if (totalTokens != null) 'total_tokens': totalTokens,
if (reasoningTokens != null) 'reasoning_tokens': reasoningTokens,
};