This issue occuring now for a few days, i dont have any idea or solution yet.
I started toying with netbeans for a few days in order to test switching from Eclipse.
After finishing my research I installed last version of Eclipse Eclipse IDE for Enterprise Java Developers - 2020-03. The issue occurs in Hydra Version 18.104.22.1689 and also in Version 22.214.171.1243. I guess it will also happen in Stable version (untested since importer had a bug with code generator in delphi).
I use OpenJDK from https://jdk.java.net/13/ for running eclipse. As JRE-Compiler in Eclipse i tried JDK13.0.2 64-Bit, JRE 8.0.241 32-Bit (in order to test if its the issue). Hydra in Delphi points towards JRE 8.0.241 32-Bit. I´ve written a new test plugin in order to test some performance with json requests but also tried to import the previous displayed Java Plugin this threads :
So i believe my written sample should be working.