code: public Authorizations addPermission(String permission) {
          this.permissions.add(new Permission(permission));
          this.aggregatePermissions = null;
  
          return this;
      }
docs: Adds (assigns) a permission to those directly associated with the Account.  If the Account doesn't yet have any
  direct permissions, a new permission collection (a Set&lt;String&gt;) will be created automatically.
  
  @param permission the permission to add to those directly assigned to the Account.