All classes are registered in the scope that corresponds to C++ namespace or exported class.
Example:
cv::ml::Boost is exported as cv.ml.Boost
cv::SimpleBlobDetector::Params is exported as cv.SimpleBlobDetector.Params

For backward compatibility all classes are registered in the global module with their mangling name containing scope information. Example:
cv::ml::Boost has cv.ml_Boost alias to cv.ml.Boost type

Closes #14730

Backport for 4.x is required to handle GAPI aliases in the right way:

cv.gapi.wip.draw.Rect = cv.gapi_wip_draw_Rect
cv.gapi.wip.draw.Text = cv.gapi_wip_draw_Text
cv.gapi.wip.draw.Circle = cv.gapi_wip_draw_Circle
cv.gapi.wip.draw.Line = cv.gapi_wip_draw_Line
cv.gapi.wip.draw.Mosaic = cv.gapi_wip_draw_Mosaic
cv.gapi.wip.draw.Image = cv.gapi_wip_draw_Image
cv.gapi.wip.draw.Poly = cv.gapi_wip_draw_Poly

cv.gapi.streaming.queue_capacity = cv.

Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

• I agree to contribute to the project under Apache 2 License.
• To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
• The PR is proposed to the proper branch
• There is a reference to the original bug report and related work
• There is accuracy test, performance test and test data in opencv_extra repository, if applicable
  Patch to opencv_extra has the same branch name.
• The feature is well documented and sample code can be built with the project CMake