Indexing nested documents giving back unrelated parents when asking for children

[Fabien Renaud]

Hello,

I'm wondering if I missed something in my code (which uses solrj 6.3):

public class Main {

    private SolrClient client1;

    public void run() {
        client1 = new 
HttpSolrClient.Builder("http://localhost:8983/solr";).build();

        SolrInputDocument doc1 = new SolrInputDocument();

        doc1.addField("id", "1");
        doc1.addField("type_s", "up");
        SolrInputDocument doc2 = new SolrInputDocument();

        doc2.addField("id", "2");
        doc2.addField("type_s", "down");

        doc1.addChildDocument(doc2);

        SolrInputDocument doc4 = new SolrInputDocument();
        doc4.addField("id", "4");
        doc4.addField("type_s", "up");

        SolrInputDocument doc5 = new SolrInputDocument();
        doc5.addField("id", "5");
        doc5.addField("type_s", "down");

        doc4.addChildDocument(doc5);

        try {
            client1.add("techproducts", Arrays.asList(doc1,doc4));
        } catch (Exception e) {
            System.out.println("Indexing failed" + e);
        }
    }

If I start Solr 6.3 using bin/start start -e techproduct and ask the following:

http://localhost:8983/solr/techproducts/select?fl=*,[child%20parentFilter=type_s:down]&fq=type_s:down&indent=on&q=*:*&wt=json


then I get:

    {
      "docs": [
        {
          "id": "2",
          "type_s": "down"
        },
        {
          "id": "5",
          "type_s": "down",
          "_childDocuments_": [
            {
              "id": "1",
              "type_s": "up"
            }
          ]
        }
      ]
    }

which seems to be a bug for me. Or did I miss something?
Notice that the relations "2 is a child of 1" and "5 is a child of 4" are 
working fine. It's just that I get extra (unwanted and unrelated) relations.

Notice that at some point I manage to get back two documents with the __same__ 
id (with different version). I'm not able to reproduce this but I guess it 
could be related.

Fabien