Marks an individual type, all types in a package or all types in a module as non-null.
Assigning null to an instance of a type marked as @nonnull is an error.
Passing null as a method argument of a type marked as @nonnull is an error.
Marks an individual type, a field or a parameter as nullable.
Assigning null to a field of a type not marked as @nullable is a warning,
except when the type itself has been marked with @nonnull, in which case it is an error.
Passing null as a method argument of a type not marked as @nullable is a warning,
except when the type itself has been marked with @nonnull, in which case it is an error.
Marks all parameters a package or module as immutable.
Assigning a value to a parameter marked as @immutable is an error.
Marks a parameter or local variable as mutable.
Assigning a value to a parameter or local variable is a warning,
except when the parameter is marked as @immutable, in which case it is an error.