@type t() :: %PolarExpress.Schemas.MeterCreate{
  aggregation:
    PolarExpress.Schemas.CountAggregation.t()
    | PolarExpress.Schemas.PropertyAggregation.t()
    | PolarExpress.Schemas.UniqueAggregation.t()
    | nil,
  custom_label: String.t() | nil,
  custom_multiplier: integer() | nil,
  filter: PolarExpress.Schemas.Filter.t() | nil,
  metadata:
    %{
      required(String.t()) => String.t() | integer() | float() | boolean() | nil
    }
    | nil,
  name: String.t() | nil,
  organization_id: String.t() | nil,
  unit: PolarExpress.Schemas.MeterUnit.t() | nil
}

• aggregation - The aggregation to apply on the filtered events to calculate the meter.
• custom_label - The label for the custom unit, e.g. 'request'. Required when unit is 'custom'. Nullable.
• custom_multiplier - The multiplier to convert from the base unit to display scale, e.g. 1000 to display per 1000 units. Defaults to 1 when not provided. Nullable.
• filter - The filter to apply on events that'll be used to calculate the meter.
• metadata - Key-value object allowing you to store additional information.

The key must be a string with a maximum length of 40 characters. The value must be either:

• A string with a maximum length of 500 characters
• An integer
• A floating-point number
• A boolean

You can store up to 50 key-value pairs.

• name - The name of the meter. Will be shown on customer's invoices and usage.
• organization_id - The ID of the organization owning the meter. Required unless you use an organization token. Nullable.
• unit - The unit of the meter.