code: @Override
      public void visitClassContext(ClassContext classContext) {
          try {
              classVersion = classContext.getJavaClass().getMajor();
              if (classVersion >= Const.MAJOR_1_4) {
                  stack = new OpcodeStack();
                  super.visitClassContext(classContext);
              }
          } finally {
              stack = null;
          }
      }
docs: implements the visitor to make sure the class is at least 1.4, and if so continues, reseting the opcode stack
  
  @param classContext
  the currently parsed java class