code: def test_list_with_one_empty_list(self):
      joiner = DocumentJoiner()
      documents = [
          Document(content="a"),
          Document(content="b"),
          Document(content="c"),
      ]
      result = joiner.run([[], documents])
      assert result == {"documents": documents}
  
file_path: haystack/test/components/joiners/test_document_joiner.py
imports: import logging
  import pytest
  from haystack import Document
  from haystack.components.joiners.document_joiner import DocumentJoiner
label_desc: Use image node_id 5 for calling the TestDocumentJoiner obj's underlying member method code with example usage: obj.test_list_with_one_empty_list() without return types