Missing move assignment operator

This class does not have a user-written move assignment operator and its copy assignment operator is found to be applied to rvalue(s), which can be moved to possibly enhance program performance had the move assignment operator been in place. Class lacks a user-written move assignment operator
/src/mongo/db/storage/ephemeral_for_test/ephemeral_for_test_radix_store.h:93: MISSING_MOVE_ASSIGNMENT 115956 Class "mongo::ephemeral_for_test::RadixStore<std::_cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > >::radix_iterator<std::pair<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const *, std::pair<std::cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > const, std::_cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> > > const &>" may benefit from adding a move assignment operator. See other events which show the copy assignment operator being applied to rvalue(s), where a move assignment may be faster.