Using apache-netbeans-java-12.3.380.vsix, Java 8 via graalVM, Maven Micronaut application.
Just playing with some simple Java code, occasionally invoking Ctrl+Click to a JDK class. Each time the JDK code is scanned for problems and added to the Problems view, eventually showing duplicated items.
Is it necessary to report problems in JDK here at all? Definitely should not be duplicated (actually multiple occurences of the same class).
Even worse - the items are being added to the Problems view just by Ctrl+hover over the class/method!
See the attached screenshot.