Place the .class folder in a subdirectory of your project with the correct package structure. Refresh the project so that eclipse picks up the new directory.

A Java class loader works by converting a class file into a Java class that can be executed by the JVM. The three primary types of class loaders in Java are as follows: ...

It seems were trying to access a field reflexively that doesn't exist: java.lang.NoSuchFieldException: value at java.base/java.lang.Class.getDeclaredField (Class.java:2384) at org.eclipse.jdt.core.dom ...