[Bug] Type loss/erasure in compiled domain classes severely hurts interoperability

[tajobe]

Describe the bug When invoking joern as a library (like in joernio/standalone-ext), the loss of type information across many domain classes breaks JVM-langauge interop, particularly with the switch to the EMT to provide property/traversal implicits.

For example, the generated Method node is compiled as (from javap, removing the fully qualified names for readability):

public class Method extends StoredNode implements MethodBase, CfgNode, Declaration

Because it doesn't have StaticType[MethodEMT] when compiled, it lacks all of those traits like HasFilenameEMT or HasFullNameEMT. This means there's no way for a Method node to satisfy the type constraints on traversals like

public final <NodeType extends StoredNode & StaticType<HasFullNameEMT>> Iterator<String> fullName$extension(Iterator);

---

There are other losses of type information, not exclusive to the EMTs.

For example, AstNode becomes

public interface AstNode extends AstNodeBase

...lacking StoredNode, and thus lacking the .file implicit/extension.

Also, there are several cases where traversals' types get widened from Iterator<Int> or Iterator<Boolean> to Iterator<Object>:

  public Iterator<Object> offsetEnd(); // should return Iterator<int>...
  public Iterator<NodeType> offsetEnd(int); // param correctly an int
  public Iterator<NodeType> offsetEnd(Seq<Object>); // param is a seq of Objects?

To Reproduce Steps to reproduce the behavior:

1. Look at classes in codepropertygraph-domain-classes_3-1.7.1.jar or generate classes using the flatgraph domain-classes-generator and compile
2. Use javap or an IDE which decompiles the classes to check signatures/types

Expected behavior Enough information is available in the compiled classes to be able to reasonably use the nodes/traversals/etc

Screenshots N/A

Desktop (please complete the following information): Should be irrelevant here but:

• OS: macOS 14.5
• Joern Version: 4.0.2, 4.0.8
• Java version: 17
• Scala version: 3.4.2 / 3.5.1-RC1

Additional context Add any other context about the problem here.