About the 'experimental' of 'Changed in version 1.4: Index key for glossary term should be considered experimental' - python-sphinx

Question

question
https://www.sphinx-doc.org/en/master/usage/restructuredtext/directives.html
About the 'experimental' of 'Changed in version 1.4: Index key for glossary term should be considered experimental.'
What puts index key on 'experimental'?
confirmed
Editing glossary with index key, 'make clean' was needed before 'make html'. Or, the index key disappeared from genindex.html.
I guess that all of the follwing testcase shuold be passed. the first testcase is related with 'make clean'. They are passed at all, on a new indexer.
#!/usr/bin/python
import unittest
from sphinx.environment.adapters.indexentries import IndexEntries
testcase01i = {
'doc1': [
('single', 'aaa', 'id-111', '', 'clf1'),
('single', 'bbb', 'id-112', '', None),
],
'doc2': [
('single', 'aaa', 'id-121', '', None),
('single', 'bbb', 'id-122', '', 'clf2'),
], }
testcase01o = [
('clf1',
[('aaa', [[('', 'doc1.html#id-111'), ('', 'doc2.html#id-121')], [], 'clf1']), ]
),
('clf2',
[('bbb', [[('', 'doc1.html#id-112'), ('', 'doc2.html#id-122')], [], None]), ]
),
]
testcase02i = {
'doc1': [
('see','hogehoge; foo','id-211','main',None),
('seealso','hogehoge; bar','id-212','main',None), ]
}
testcase02o = [
('H',
[('hogehoge',
[[],
[('see also bar', []), ('see foo', [])],
None
])
])
]
testcase03i = {
'doc1': [
('single','func1() (aaa module)','id-311','',None),
('single','func1() (bbb module)','id-312','',None),
('single','func1() (ccc module)','id-313','',None),]
}
testcase03o = [
('F',
[('func1()',
[[],
[('(aaa module)', [('', 'doc1.html#id-311')]),
('(bbb module)', [('', 'doc1.html#id-312')]),
('(ccc module)', [('', 'doc1.html#id-313')])
],
None])])
]
testcase04i = {
'doc1': [
('single','func1() (aaa module)','id-411','',None),
('single','func1() (bbb module)','id-412','',None),
('single','func1() (ccc module)','id-413','main',None), ]
}
testcase04o = [
('F',
[('func1()',
[[],
[('(aaa module)', [('', 'doc1.html#id-411')]),
('(bbb module)', [('', 'doc1.html#id-412')]),
('(ccc module)', [('main', 'doc1.html#id-413')]), ],
None])])
]
#-------------------------------------------------------------------
class _domain(object):
def __init__(self, entries):
self.entries = entries
class _env(object):
def __init__(self, domain):
self.domain = {}
self.domain['index'] = domain
def get_domain(self, domain_type):
return self.domain[domain_type]
class _builder(object):
def get_relative_uri(self, uri_type, file_name):
return f'{file_name}.html'
#-------------------------------------------------------------------
bld = _builder()
class TestcaseIndexEntries(unittest.TestCase):
def test01_classifier(self):
self.maxDiff = None
dmn = _domain(testcase01i)
env = _env(dmn)
gidx = IndexEntries(env).create_index(bld)
self.assertEqual(testcase01o, gidx)
def test02_see_and_seealso(self):
self.maxDiff = None
dmn = _domain(testcase02i)
env = _env(dmn)
gidx = IndexEntries(env).create_index(bld)
self.assertEqual(testcase02o, gidx)
def test03_homonymous_function(self):
self.maxDiff = None
dmn = _domain(testcase03i)
env = _env(dmn)
gidx = IndexEntries(env).create_index(bld)
self.assertEqual(testcase03o, gidx)
def test04_homonymous_function(self):
self.maxDiff = None
dmn = _domain(testcase04i)
env = _env(dmn)
gidx = IndexEntries(env).create_index(bld)
self.assertEqual(testcase04o, gidx)
#-------------------------------------------------------------------
if __name__ == '__main__':
unittest.main()
purpose
I want to know which there is some other puting index key on 'experimental'. If there is it, I want to see if it is fixed by the indexer.
note
I am writing this using a translation software. If there is anything difficult to understand, I will add it.