Android: sshd library is very old and should be updated
The Remote File Browser plugin works by running an SFTP server on Android and connecting to it using SSHFS from the desktop.
The SFTP server implementation we use in Android is from Apache mina-sshd. This is a Java library. However, due to some differences in the way to access the filesystem in Android, the latest version we managed to get working is 0.14 from 2015.
The goal of this task is to upgrade to a recent version. You can see all the released versions here: https://mvnrepository.com/artifact/org.apache.sshd/sshd-core
One API that newer versions of Apache Mina use is java.nio.file, which wasn't available in Android until API 26. We currently support down to API 21, but we can bump the requirement to API 26 if required to update this library (maybe nio file can be dessugared, though?). In any case, there probably are more incompatibilities that we need to solve to be able to upgrade.