code: func (rules *ClientConfigLoadingRules) GetDefaultFilename() string {
  	// Explicit file if we have one.
  	if rules.IsExplicitFile() {
  		return rules.GetExplicitFile()
  	}
  	// Otherwise, first existing file from precedence.
  	for _, filename := range rules.GetLoadingPrecedence() {
  		if _, err := os.Stat(filename); err == nil {
  			return filename
  		}
  	}
  	// If none exists, use the first from precedence.
  	if len(rules.Precedence) > 0 {
  		return rules.Precedence[0]
  	}
  	return ""
  }
docs: // GetDefaultFilename implements ConfigAccess