6 methods override FilterPluginBase::operator_form() in Views (for Drupal 7) 8.3

Access::operator_form in lib/Views/node/Plugin/views/filter/Access.php

Options form subform for setting the operator.

BooleanOperator::operator_form in lib/Drupal/views/Plugin/views/filter/BooleanOperator.php

Options form subform for setting the operator.

NodeTnid::operator_form in lib/Views/translation/Plugin/views/filter/NodeTnid.php

Provide simple boolean operator

NodeTnidChild::operator_form in lib/Views/translation/Plugin/views/filter/NodeTnidChild.php

Options form subform for setting the operator.

Search::operator_form in lib/Views/search/Plugin/views/filter/Search.php

Provide simple equality operator

Status::operator_form in lib/Views/node/Plugin/views/filter/Status.php

Options form subform for setting the operator.