Does openfl don't overwrite flash API?

Hello. For flash target, openfl.display.BitmapData is instead flash.display.BitmapData:

var bitmapData = new openfl.display.BitmapData(500, 500, false, 0x00000000);
trace(Type.getClassName(Type.getClass(bitmapData))); //flash.display.BitmapData

I’d like to know - where is this behaviour defined?

Oh, should’ve searched through externs too. Found the answer:

And vice versa, in case you type flash.display.BitmapData and compile for something besides Flash: