20 files declare their use of FieldPluginBase

CckFieldPluginBase.php in core/modules/migrate_drupal/src/Plugin/migrate/cckfield/CckFieldPluginBase.php
D6FileField.php in core/modules/migrate_drupal/tests/modules/migrate_field_plugin_manager_test/src/Plugin/migrate/field/D6FileField.php
D6NoCoreVersionSpecified.php in core/modules/migrate_drupal/tests/modules/migrate_field_plugin_manager_test/src/Plugin/migrate/field/D6NoCoreVersionSpecified.php
DateField.php in core/modules/datetime/src/Plugin/migrate/field/d6/DateField.php
DateField.php in core/modules/datetime/src/Plugin/migrate/field/DateField.php
Email.php in core/modules/field/src/Plugin/migrate/field/Email.php
EntityReference.php in core/modules/field/src/Plugin/migrate/field/d7/EntityReference.php
FieldLeft.php in core/modules/migrate_drupal/tests/modules/migrate_state_finished_test/src/Plugin/migrate/field/FieldLeft.php
FieldRight.php in core/modules/migrate_drupal/tests/modules/migrate_state_finished_test/src/Plugin/migrate/field/FieldRight.php
FileField.php in core/modules/file/src/Plugin/migrate/field/d6/FileField.php
ImageField.php in core/modules/image/src/Plugin/migrate/field/d7/ImageField.php
LinkField.php in core/modules/link/src/Plugin/migrate/field/d6/LinkField.php
ListField.php in core/modules/options/src/Plugin/migrate/field/d7/ListField.php
NumberField.php in core/modules/field/src/Plugin/migrate/field/d7/NumberField.php
OptionsField.php in core/modules/options/src/Plugin/migrate/field/d7/OptionsField.php
OptionWidgetsField.php in core/modules/options/src/Plugin/migrate/field/d6/OptionWidgetsField.php
PhoneField.php in core/modules/telephone/src/Plugin/migrate/field/d7/PhoneField.php
TaxonomyTermReference.php in core/modules/taxonomy/src/Plugin/migrate/field/TaxonomyTermReference.php
TextField.php in core/modules/text/src/Plugin/migrate/field/d7/TextField.php
TextField.php in core/modules/text/src/Plugin/migrate/field/d6/TextField.php

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