Function generate_json_output_with_diff 

pub fn generate_json_output_with_diff<W: Write>(
    metrics: &ProjectMetrics,
    thresholds: &IssueThresholds,
    manifest: &AnalysisManifest,
    diff: &BaselineDiff,
    writer: &mut W,
) -> Result<()>

Generate complete JSON output with a top-level baseline diff object.