This annotation can be applied to a package, type, method or constructor in order to
define that contained entities for which a null annotation is otherwise lacking
should be considered as @NonNull. Entities affected by
method return values
parameters of a method or constructor
Local variables are not affected.
Canceling a default
By using a @NonNullByDefault annotation with the argument false,
a default from any enclosing scope can be canceled for the element being annotated.
If a @NonNullByDefault
annotation is used within the scope of another @NonNullByDefault
annotation, the innermost annotation defines the
default applicable at any given position (depending on the parameter value()).
Note that for applying an annotation to a package, a file by the name
package-info.java is used.