@type t() :: %EveESI.Model.GetSovereigntyStructures200Ok{
  alliance_id: integer(),
  solar_system_id: integer(),
  structure_id: integer(),
  structure_type_id: integer(),
  vulnerability_occupancy_level: float() | nil,
  vulnerable_end_time: DateTime.t() | nil,
  vulnerable_start_time: DateTime.t() | nil
}