Thats right ,there’s some little backward incopatibility between java 8 and 11.
when i look at this in your logs
[ERROR] /home/irynah/Openmrs-Projects/openmrs-core/tools/src/main/java/org/openmrs/tools/doclet/ShouldTaglet.java:[143,1] error: method does not override or implement a method from a supertype
The Old Doclet API in java 8 was deprecatd and finally removed in java 11, and replaced with another new Doclet API. This will require some little bit of refactoring some code. You can start a Talk thread about this. I would have done so , but currently i have alot of tasks am handling at the same time. cc @dkayiwa