package
statements that do not correspond to the project directory structure.
Also, reports classes without package
statements if the class is not located directly in
source root directory.
While it's not strictly mandated by Java language, it's good practise to keep classes
from package com.example.myapp
inside a com/example/myapp
directory directly under
a source root. Failure to do this may confuse code readers and make some tools work incorrectly.