It's missing from advertised mechanisms
2020-05-13 00:14:24 | jaxmpp_ :: jaxmpp__4g72t30025@localhost << <features xmlns="http://etherx.jabber.org/streams"><sm xmlns="urn:xmpp:sm:3"/><auth xmlns="http://jabber.org/features/iq-auth"/><register xmlns="http://jabber.org/features/iq-register"/><mechanisms xmlns="urn:ietf:params:xml:ns:xmpp-sasl"><mechanism>SCRAM-SHA-256</mechanism><mechanism>SCRAM-SHA-1</mechanism><mechanism>PLAIN</mechanism><mechanism>ANONYMOUS</mechanism></mechanisms><ver xmlns="urn:xmpp:features:rosterver"/><sub xmlns="urn:xmpp:features:pre-approval"/><compression xmlns="http://jabber.org/features/compress"><method>zlib</method></compression></features>
I've fixed that with #server-1151
It's missing from advertised mechanisms