Returns the fully qualified package name.
If this class is a top level class, then this method returns the fully qualified name of the package that the class is a member of, or the empty string if the class is in an unnamed package.
If this class is a member class, then this method is equivalent to
getPackageName() on the
If this class represents an array type then this method returns the
package name of the element type. If this class represents a primitive
type or void then the package name "
java.lang" is returned.
@jls 6.7 Fully Qualified Names