[Bug] < in header not escaped when outputFormat: "markdown"

[bohyunjung]

Describe the bug

A rendered markdown file includes unescaped <.
And my markdown parser (docusaurus) fails to parse the file.

Here's a header line that includes unescaped <.

# <a id="Newtonsoft_Json_Generated_CustomBinding0_4"></a> Delegate CustomBinding0<TSelf, T0, T1, T2\>

To Reproduce
Steps to reproduce the behavior:

Run docfx with metadata.outputFormat: "markdown" option.

Whole docfx.json

{
  "metadata": [
    {
      "src": [
        {
          "src": "..",
          "files": [
            "**/*.cs"
          ]
        }
      ],
      "dest": "api",
      "globalNamespaceId": "Global",
      "allowCompilationErrors": true,
      "namespaceLayout": "nested",
      "outputFormat": "markdown"
    }
  ]
}

Expected behavior

Since > is escaped as follows, the escape of < is also expected.

CustomBinding0<TSelf, T0, T1, T2\>

Context (please complete the following information):

• OS: macOS 14.2.1(23C71)
• Docfx version: 2.75.3+a5c719410037cc288c7adff010b1abf3c0f2e581
• Dotnet version: 7.0.403

Additional context

I'm working on a Unity package project, and I referenced the docfx settings of https://github.com/CaseyHofland/docfx-unitypackage.

[bohyunjung]

I'm unsure whether this is relevant, but < is not included in EscapeChars. Is it intended? @yufeih

docfx/src/Docfx.Build/ApiPage/ApiPageMarkdownTemplate.cs

Line 101 in 7d511fb

const string EscapeChars = "\\`*_{}[]()#+-!>~\"'";

[yufeih]

< shows up correctly in your example using vscode markdown preview and it should comply with markdown standard. What markdown engine did you see problems rendering the content?

For context, escaping one angle bracket should prevent it from becoming an HTML tag, and > is used for blockquote syntax hence it is escape.

[bohyunjung]

My bad. I was using the mdx parser in my docusaurus config. After setting it to md, it parses the docfx-generated markdown file without error.

Thank you.