Redmine

if an issue IS NOT private，using "GET /issues/<this_issue_id>.xml" can get "<is_private>false</is_private>" in the response;but if using "GET /issues/<this_issue_id>.json", there is no "is_private" key fonud in the response.

and the similar:
if a project IS NOT public，using "GET /projects/<this_project_id>.xml" can get "<is_public>false</is_public>" in the response;but if using "GET /issues/<this_project_id>.json", there is no "is_public" key fonud in the response.

Environment:
Redmine version 2.6.6.stable
Ruby version 2.0.0-p645 (2015-04-13) [x86_64-linux]
Rails version 3.2.22
Environment production
Database adapter Mysql2
SCM:
Subversion 1.7.10
Filesystem
Redmine plugins:
redmine_cas 1.2.1