20 files declare their use of Feed in Drupal 8

aggregator.module in core/modules/aggregator/aggregator.module

Used to aggregate syndicated content (RSS, RDF, and Atom).

AggregatorFeedViewsFieldAccessTest.php in core/modules/aggregator/tests/src/Kernel/Views/AggregatorFeedViewsFieldAccessTest.php

AggregatorItemViewsFieldAccessTest.php in core/modules/aggregator/tests/src/Kernel/Views/AggregatorItemViewsFieldAccessTest.php

AggregatorTestBase.php in core/modules/aggregator/src/Tests/AggregatorTestBase.php

AggregatorTestBase.php in core/modules/aggregator/tests/src/Functional/AggregatorTestBase.php

AggregatorTitleTest.php in core/modules/aggregator/tests/src/Kernel/AggregatorTitleTest.php

FeedCacheTagsTest.php in core/modules/aggregator/tests/src/Functional/FeedCacheTagsTest.php

FeedParserTest.php in core/modules/aggregator/tests/src/Functional/FeedParserTest.php

FeedProcessorPluginTest.php in core/modules/aggregator/tests/src/Functional/FeedProcessorPluginTest.php

FeedResourceTestBase.php in core/modules/aggregator/tests/src/Functional/Rest/FeedResourceTestBase.php

FeedTest.php in core/modules/jsonapi/tests/src/Functional/FeedTest.php

FeedValidationTest.php in core/modules/aggregator/tests/src/Kernel/FeedValidationTest.php

ImportOpmlTest.php in core/modules/aggregator/tests/src/Functional/ImportOpmlTest.php

ItemCacheTagsTest.php in core/modules/aggregator/tests/src/Functional/ItemCacheTagsTest.php

ItemHalJsonTestBase.php in core/modules/aggregator/tests/src/Functional/Hal/ItemHalJsonTestBase.php

ItemResourceTestBase.php in core/modules/aggregator/tests/src/Functional/Rest/ItemResourceTestBase.php

ItemTest.php in core/modules/jsonapi/tests/src/Functional/ItemTest.php

MigrateAggregatorFeedTest.php in core/modules/aggregator/tests/src/Kernel/Migrate/d6/MigrateAggregatorFeedTest.php

MigrateAggregatorFeedTest.php in core/modules/aggregator/tests/src/Kernel/Migrate/d7/MigrateAggregatorFeedTest.php

UpdateFeedItemTest.php in core/modules/aggregator/tests/src/Functional/UpdateFeedItemTest.php