Typed Inttegro domain value.
@type t() :: %Inttegro.Invoices.InvoiceSettings{ custom_data: %{optional(String.t()) => String.t()} | nil, footer: String.t() | nil, memo: String.t() | nil, number: String.t() | nil }
@spec from_map(map()) :: t()
@spec new!(map() | keyword()) :: t()
@spec to_map(t()) :: map()