RCS1097 False Negative 4

RCS1097 isn't flagged on ```address.ToString()```. Is this a false negative?

```csharp
using System.Net;
using System.Text;

namespace RCS1097_False_Negative
{
static class Class
{
static void M(IPAddress[] ipaddressarray)
{
StringBuilder addressList = new StringBuilder();
foreach (IPAddress address in ipaddressarray)
{
addressList.Append(address.ToString());
}
}
}
}
```

Reproduce the RCS1097 case from this issue using the provided C# example, focusing on address.ToString() inside StringBuilder.Append. Trace the analyzer behavior for this expression and determine whether it should be flagged; done means the expected diagnostic behavior is covered by an appropriate regression test.

Written by the indexing model from the issue text.