code: @Override
      public void visitClassContext(ClassContext classContext) {
          try {
              JavaClass cls = classContext.getJavaClass();
              constrainingMethods = buildConstrainingMethods(cls);
              AnnotationEntry[] annotations = cls.getAnnotationEntries();
              classHasAnnotation = !CollectionUtils.isEmpty(annotations);
              stack = new OpcodeStack();
              selfCallTree = new HashMap<>();
              super.visitClassContext(classContext);
  
              performModifyStateClosure(classContext.getJavaClass());
  
          } finally {
              stack = null;
              selfCallTree = null;
              curMethod = null;
              constrainingMethods = null;
          }
      }
docs: implements the visitor to collect statistics on this class
  
  @param classContext
  the currently class