The following subsasgn command fails on Octave (5.x - 9.x) but works fine on MATLAB

a=containers.Map();
subsasgn(a, struct('type', '()', 'subs', 'testkey'), 1)

octave error:

 error: sq_string cannot be indexed with {
 error: called from
    subsasgn at line 462 column 15

 
similarly, the ('testkey') operator also fails to work in subsref to retrieve values if the key exist

 a('test')=1
 subsref(a, struct('type', '()', 'subs', 'test'))

octave error:

 error: sq_string cannot be indexed with {
 error: called from
    subsref at line 432 column 15

expected behavior: if mapname('test') can be assigned and retrieved, the subsasgn and subsref interfaces should allow () operator with a string-valued key.