docs: private StringBuilder appendPostTypes(final EnumSet<Post.Type> types, final StringBuilder sql) {
        int typesCount = types != null ? types.size() : 0;
        switch(typesCount) {
           case 0:
              break;
           case 1:
              sql.append(" AND post_type=").append(String.format("'%s'", types.iterator().next().toString()));
              break;
           default:
              sql.append(" AND post_type IN (");
              sql.append(inJoiner.join(types.stream().map(t -> String.format("'%s'", t.toString())).collect(Collectors.toSet())));
              sql.append(")");
              break;
        }
  
        return sql;
     }