Summary
Finally, I found the related issue, setForeground() incorrectly flagged as requiring API 23 on ViewGroups extending FrameLayout.
If you are not extending FrameLayout, the documentation is wrong and API 23 is required.
Issue 186273: View.setForeground wrong API level
Updated question
Marked as duplicated of Can't use setForeground method on ImageView by Commonsware and answered by him:
That is a documentation bug. setForeground() existed on FrameLayout from API Level 1; it is only on View as of API Level 23.
In my case the documentation bug is not detected by the inspection in the fork but does it in an integration project, I don't understand it, anyway, this answers my initial question.
But It's not the same case, this code is already extending a Framelayout and using this method, it's not an ImageView, so I suppose the method has been removed in API 23. It doesn't appear in the reference now.
Update: I add a diff report for FrameLayout:
New question
So my question changes to how to use the method in previous versions, and, why does appear the inspection error selectively?
If I add a redundant cast, the error message disappears:
((FrameLayout) layout).getForeground()
But it's accessing the View method that is not supported now.
So I suppose targeting a previous API would remove the error message but I would appreciate a solution to use this Framelayout method or a clue to fix the issue in my case:
ANDROID_COMPILE_SDK_VERSION=23
ANDROID_BUILD_TOOLS_VERSION=23.0.1
ANDROID_DEFAULT_MIN_SDK_VERSION=19
ANDROID_DEFAULT_TARGET_SDK_VERSION=23
Workaround
In short, as a workaround, I changed the type to FrameLayout directly, so warnings about API and casting are gone, and I tested it works on Android 4.4.4 device and debugging, I thought it would crash, anyway it's only used in one animation, and I will fix/replace it in the future.
Initial question
I forked and customised the Google sample android-topeka, and android-studio shows an error that I don't understand about the API level required to use the method getForeground() of the class View in android.view package:
Call requires API level 23 (current min is 19): android.view.View#getForeground
The reference marks the method as added in API level 1, and the documentation (Control+Q) shows the same:
But the Calling new methods on older versions inspection shows an error that API level 23 is required:
I found a similar question, a bug in that case, but I think this is not a bug due to the original fork doesn't show this error message.
I'll try to detect the first time the message appears, but I did a lot of changes so any clue would be appreciated, thanks.