17 files declare their use of AllowedHtmlInterface in Markdown 8.2

AllowedHtmlManager.php in src/PluginManager/AllowedHtmlManager.php

Cmark.php in src/Plugin/Markdown/Pecl/Cmark.php

CommonMark.php in src/Plugin/Markdown/CommonMark/CommonMark.php

EmojiExtension.php in src/Plugin/Markdown/CommonMark/Extension/EmojiExtension.php

ExternalLinkExtension.php in src/Plugin/Markdown/CommonMark/Extension/ExternalLinkExtension.php

FilterAlign.php in src/Plugin/Markdown/AllowedHtml/FilterAlign.php

FilterCaption.php in src/Plugin/Markdown/AllowedHtml/FilterCaption.php

FootnoteExtension.php in src/Plugin/Markdown/CommonMark/Extension/FootnoteExtension.php

HeadingPermalinkExtension.php in src/Plugin/Markdown/CommonMark/Extension/HeadingPermalinkExtension.php

MarkdownParamConverter.php in src/ParamConverter/MarkdownParamConverter.php

MediaEmbed.php in src/Plugin/Markdown/AllowedHtml/MediaEmbed.php

Parsedown.php in src/Plugin/Markdown/Parsedown/Parsedown.php

PhpMarkdown.php in src/Plugin/Markdown/PhpMarkdown/PhpMarkdown.php

PhpMarkdownExtra.php in src/Plugin/Markdown/PhpMarkdown/PhpMarkdownExtra.php

StrikethroughExtension.php in src/Plugin/Markdown/CommonMark/Extension/StrikethroughExtension.php

TableExtension.php in src/Plugin/Markdown/CommonMark/Extension/TableExtension.php

TaskListExtension.php in src/Plugin/Markdown/CommonMark/Extension/TaskListExtension.php