HTTP 500 error when trying v3.1 /sessions in API explorer

Bug description

When trying these endpoints in the API explorer under http://openam.example.com:8080/openam/XUI/#api/explorer/sessions:

• /sessions#2.1_query_filter
• /sessions#3.1_query_filter

with _queryFilter=true, I get HTTP 500 errors.

For example:

How to reproduce the issue

1. Set up with the default configuration.
2. Login as amadmin.
3. Open the API explorer.
4. Navigate to http://openam.example.com:8080/openam/XUI/#api/explorer/sessions.
5. Try the endpoints with _queryFilter=true.

Expected behaviour

Successful response listing open sessions.

Current behaviour

HTTP 500 errors.

It appears that the request URL is missing the realm in the root, e.g. /json/realms/root/sessions.