Reports references to non-constant private members of a different class, for which javac will generate a package-private synthetic accessor method.
An inner class and its containing class are compiled to separate class files. The Java virtual machine normally prohibits access from a class to private fields and methods of another class. To enable access from an inner class to private members of a containing class or the other way around javac creates a package-private synthetic accessor method. Less use of memory and greater performance may be achieved by making the member package-private, thus allowing direct access without the creation of a synthetic accessor method.
This inspection does not report anything if language level is set to Java 11 or higher as thanks to nest-based access control (JEP 181), accessor methods are not generated anymore.