constructor(database, currVersion, newVersion) {
    /** @private @const {!Array<!VersionRenamer>} */
    this.versionRenamers_ = Renamer.calculateRenamings(
      database,
      currVersion,
      newVersion,
    );
  }
Constructor for the class.
@param {!Object} database The database of renames.
@param {string} currVersion The version to migrate from.
@param {string} newVersion The version to migrate to.