9 files declare their use of PluginDefinitionInterface in Plugin 8.2

ArrayPluginDefinitionDecoratorTest.php in tests/src/Unit/PluginDefinition/ArrayPluginDefinitionDecoratorTest.php

MergeablePluginDefinitionTraitTest.php in tests/src/Unit/PluginDefinition/MergeablePluginDefinitionTraitTest.php

PluginHierarchyTrait.php in src/PluginHierarchyTrait.php

PluginIdTest.php in tests/src/Unit/Plugin/views/filter/PluginIdTest.php

PluginLabelTest.php in tests/src/Unit/Plugin/Field/FieldFormatter/PluginLabelTest.php

PluginType.php in src/PluginType/PluginType.php

PluginTypeTest.php in tests/src/Unit/PluginType/PluginTypeTest.php

SelectListTest.php in tests/src/Unit/Plugin/Plugin/PluginSelector/SelectListTest.php

TypedDefinitionEnsuringPluginDiscoveryDecoratorTest.php in tests/src/Unit/PluginDiscovery/TypedDefinitionEnsuringPluginDiscoveryDecoratorTest.php