CA2122: Do not indirectly expose methods with references. How to fix this in my code

Question

CA2122: Do not indirectly expose methods with references.

My code is as follows:

public void LoadPage(Uri url)
{
    webBrowser1.Url = url;    //webBrowser1 is an object of WebBrowser
    webBrowser1.Refresh();
}

Fxcop issued the warning "CA2122: Do not indirectly expose methods with references."

• Why did this warning appear in my code?

• How to fix it?

• How can I grant permission to my code for the full security access code (CAS) attribute. ie I have an attribute for a method like this [EnvironmentPermissionAttribute (SecurityAction.LinkDemand, Unrestricted = false)]

What permission do I have for my code and how for the above attribute?