/**
 * Inverse of HasOneThrough/HasManyThrough: this model holds a foreignKey that points
 * to an intermediate (through) model, which in turn holds a throughForeignKey that
 * points to the related model.
 *
 * Example: Profile → BelongsToThrough → Country through User
 *   - Profile.foreignKey      (userId)    → User.localKey        (id)
 *   - User.throughForeignKey  (countryId) → Country.throughLocalKey (id)
 *
 * @param related          - Lazy getter for the final related entity class
 * @param through          - Lazy getter for the intermediate entity class
 * @param foreignKey       - FK on this model pointing to through's localKey
 * @param throughForeignKey - FK on the through model pointing to related's throughLocalKey
 * @param localKey         - PK on the through model that foreignKey references (default 'id')
 * @param throughLocalKey  - PK on the related model that throughForeignKey references (default 'id')
 */
export declare function BelongsToThrough(related: () => any, through: () => any, foreignKey: string, throughForeignKey: string, localKey?: string, throughLocalKey?: string): PropertyDecorator;