code: @Override
      public void visitClassContext(ClassContext classContext) {
          try {
              stack = new OpcodeStack();
              nodeCreations = new HashMap<>();
              nodeStores = new HashMap<>();
              super.visitClassContext(classContext);
          } finally {
              stack = null;
              nodeCreations = null;
              nodeStores = null;
          }
      }
docs: implements the visitor to create and clear the stack, node creations and store maps
  
  @param classContext
  the context object for the currently parsed class