toString method
A string representation of this object.
Some classes have a default textual representation,
often paired with a static parse function (like int.parse).
These classes will provide the textual representation as
their string representation.
Other classes have no meaningful textual representation
that a program will care about.
Such classes will typically override toString to provide
useful information when inspecting the object,
mainly for debugging or logging.
Implementation
@override
String toString() {
  final $buf = StringBuffer()..writeln('PriceRecurring(');
  if (aggregateUsage != null) {
    $buf
      ..writeln()
      ..write('  aggregate_usage: ')
      ..write(aggregateUsage)
      ..write(',');
  }
  $buf
    ..writeln()
    ..write('  interval: ')
    ..write(interval)
    ..write(',');
  if (intervalCount != null) {
    $buf
      ..writeln()
      ..write('  interval_count: ')
      ..write(intervalCount)
      ..write(',');
  }
  if (meter != null) {
    $buf
      ..writeln()
      ..write('  meter: ')
      ..write(meter)
      ..write(',');
  }
  if (trialPeriodDays != null) {
    $buf
      ..writeln()
      ..write('  trial_period_days: ')
      ..write(trialPeriodDays)
      ..write(',');
  }
  if (usageType != null) {
    $buf
      ..writeln()
      ..write('  usage_type: ')
      ..write(usageType)
      ..write(',');
  }
  $buf.write(')');
  return $buf.toString();
}