6 classes are annotated with ViewsArgumentValidator in Drupal 8

ArgumentValidatorTest in core/modules/views/tests/modules/views_test_data/src/Plugin/views/argument_validator/ArgumentValidatorTest.php

Defines a argument validator test plugin.

Entity in core/modules/views/src/Plugin/views/argument_validator/Entity.php

Defines a argument validator plugin for each entity type.

None in core/modules/views/src/Plugin/views/argument_validator/None.php

Do not validate the argument.

NumericArgumentValidator in core/modules/views/src/Plugin/views/argument_validator/NumericArgumentValidator.php

Validate whether an argument is numeric or not.

TermName in core/modules/taxonomy/src/Plugin/views/argument_validator/TermName.php

Validates whether a term name is a valid term argument.

UserName in core/modules/user/src/Plugin/views/argument_validator/UserName.php

Validates whether a user name is valid.