JRuby version 9.3.13.0
Platform 6.5.13-1rodete2

Expected behavior:

• There is a class org.example.C which is in a jar which is not on the class path, call this C_jar
• There is a class org.example.C which is in a jar which is on the class path, call this C_classpath
• C_jar is loaded via URLClassLoader and instantiated in Java code. This is done to isolate the different versions of C.
• Use Ruby to evaluate an object expression which results in an instance of an object with the class C_jar
• Use the Java module to reference the class C, expecting to get C_classpath (i.e. Java::OrgExample::C)

Actual behavior:

• Using the Java module syntax to access C results in C_jar

Workaround:

• Use the Java module syntax to access C before any Ruby expression which evaluates to an object of class C_jar

In Java.java, generateClassProxy calls addToJavaPackageModule without checking the class loader of the class it generated a proxy for. Effectively, manipulating values from non-JRubyClassLoader classes pollutes the Java module with incompatible classes.