code: public <A> Q from(Path<A> entity, Iterable<? extends A> col) {
          iterables.put(entity, col);
          getMetadata().addJoin(JoinType.DEFAULT, entity);
          return queryMixin.getSelf();
      }
docs: Add a query source
  
  @param <A> type of expression
  @param entity Path for the source
  @param col content of the source
  @return current object