columnar::TestUtils::BranchReaderArray< T > Node1 columnar::TestUtils ::BranchReaderArray< T > + m_branch + m_dataVec + BranchReaderArray() + BranchReaderArray() + operator=() + columnName() + containerName() + connectTree() + getEntry() Node2 std::string Node2->Node1 +m_branchName Node3 std::basic_string< char > Node3->Node2