As it look like there will be removed easy support for Java in DSM 7 (or at least it is removed in version 7.0-41882) and Ubooquity need it to be able to run I been looking if someone in Synology user community created replacement Java package.
And fortunately there is Rednoah's Java Installer.
It can be accessed on this URL https://github.com/rednoah/java-installerwhere is short description how to add it as package source in Package Center.
Unfortunately on mine DS2413+ installation from there failed but I haven't given up and downloaded most current version of spk package to computer and then uploaded it in Package center as Manual Installation. That have been successful and after some time installer reported Java installed.
I downloaded spk from https://github.com/rednoah/java-installer/releases/download/2.16/java-installer_2.16-dsm7.spk (but this URL will be most likely obsolete soon and it might be better to find most up to date url in syno-dsm7.json file on Rednoah's GitHub)
And I just had to replace path to java binaries in conf file (if used) from
/var/packages/Java8/target/j2sdk-image/bin to path where java-installer downloaded new java
and mine home Ubooquity service is back on
Customer support service by UserEcho