我有一个应用程序，它在身份验证后提供访问令牌，我想检查令牌是否未过期

@JsonProperty(access = JsonProperty.Access.WRITE_ONLY)
    private String expires_in;

public boolean isNotExpired() {
        return ! Instant.now().isBefore(Instant.parse(expires_in));
    }

但在我运行应用程序之后，我得到了错误：

JSON encoding error: Text '3600' could not be parsed at index 4; nested exception is com.fasterxml.jackson.databind.JsonMappingException: Text '3600' could not be parsed at index 4 (through reference chain: com.Auth.AuthInfo["notExpired"])

我怎样才能解决这个问题？