code: func (va *ValidationAuthorityImpl) logRemoteValidationDifferentials(
  	domain string,
  	primaryResult *probs.ProblemDetails,
  	remoteProbs []*probs.ProblemDetails) {
  
  	var successes []*probs.ProblemDetails
  	var failures []*probs.ProblemDetails
  
  	allEqual := true
  	for _, e := range remoteProbs {
  		if e != primaryResult {
  			allEqual = false
  		}
  		if e == nil {
  			successes = append(successes, nil)
  		} else {
  			failures = append(failures, e)
  		}
  	}
  	if allEqual {
  		// There's no point logging a differential line if the primary VA and remote
  		// VAs all agree.
  		return
  	}
  
  	// If the primary result was OK and there were more failures than the allowed
  	// threshold increment a stat that indicates this overall validation will have
  	// failed if features.EnforceMultiVA is enabled.
  	if primaryResult == nil && len(failures) > va.maxRemoteFailures {
  		va.metrics.prospectiveRemoteValidationFailures.Inc()
  	}
  
  	logOb := struct {
  		Domain          string
  		PrimaryResult   *probs.ProblemDetails
  		RemoteSuccesses int
  		RemoteFailures  []*probs.ProblemDetails
  	}{
  		Domain:          domain,
  		PrimaryResult:   primaryResult,
  		RemoteSuccesses: len(successes),
  		RemoteFailures:  failures,
  	}
  
  	logJSON, err := json.Marshal(logOb)
  	if err != nil {
  		// log a warning - a marshaling failure isn't expected given the data and
  		// isn't critical enough to break validation for by returning an error to
  		// the caller.
  		va.log.Warningf("Could not marshal log object in "+
  			"logRemoteValidationDifferentials: %s", err)
  		return
  	}
  
  	va.log.Infof("remoteVADifferentials JSON=%s", string(logJSON))
  }
docs: // logRemoteValidationDifferentials is called by `processRemoteResults` when the
  // `MultiVAFullResults` feature flag is enabled. It produces a JSON log line
  // that contains the primary VA result and the results each remote VA returned.