[6.1-9] MAY: Transfer-Encoding MAY be sent in a response to a HEAD request or in a 304 (Not Modified) response (S...

[saviorand]

RFC 9112 Requirement

Section: 6.1-9 Keyword: MAY

Transfer-Encoding MAY be sent in a response to a HEAD request or in a 304 (Not Modified) response (Section 15.4.5 of [HTTP]) to a GET request, neither of which includes a message body, to indicate that the origin server would have applied a transfer coding to the message body if the request had been an unconditional GET. This indication is not required, however, because any recipient on the response chain (including the origin server) can remove transfer codings when they are not needed.¶

Reference: https://www.rfc-editor.org/rfc/rfc9112.html#section-6.1-9