I wouldn't expect migrating from 17 to 25 to be an awful lot of work. The hard bump was moving from Java 8 to 9+ (11, typically), due to the introduction of the module system, removal of APIs previously shipped with the JDK (e.g. JAXB), etc. Things get much easier once you've passed this hurdle. Adopting 17 posed another, usually smaller, challenge due to reflection not working OOTB like before, but I'm not aware of other, equally disruptive changes after 17.