为什么我使用该类型。GetField()aways返回null?[副本]

我使用GetField()获取selenium PID,但当我尝试获取“ProcessId”时,它总是返回null,可以看到img,ProcessId字段不是空的。 这是我的代码:

public void tes(ChromeDriver driver) {
            var flag = System.Reflection.BindingFlags.NonPublic
                          | System.Reflection.BindingFlags.Instance;
            var executorField = typeof(OpenQA.Selenium.Remote.RemoteWebDriver)
                .GetField("executor",
                          System.Reflection.BindingFlags.NonPublic
                          | System.Reflection.BindingFlags.Instance);
            object executor = executorField.GetValue(driver);
            var Service = executor.GetType().GetField("service", System.Reflection.BindingFlags.NonPublic | System.Reflection.BindingFlags.Instance);
            object remoteServerPidField = Service.GetValue(executor);
            var pid = remoteServerPidField.GetType().GetField("ProcessId", BindingFlags.Instance | BindingFlags.Static);
        }

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