## Why is this an issue?

`StringBuilder` instances that never build a `string` clutter the code and worse are a drag on performance. Either they should be removed, or the missing `ToString()` call should be added.

### Noncompliant code example

    public void DoSomething(List<string> strings) {
      var sb = new StringBuilder();  // Noncompliant
      sb.Append("Got: ");
      foreach(var str in strings) {
        sb.Append(str).Append(", ");
        // ...
      }
    }

### Compliant solution

    public void DoSomething(List<string> strings) {
      foreach(var str in strings) {
        // ...
      }
    }

or

    public void DoSomething(List<string> strings) {
      var sb = new StringBuilder();
      sb.Append("Got: ");
      foreach(var str in strings) {
        sb.Append(str).Append(", ");
        // ...
      }
      logger.LogInformation(sb.ToString());
    }

### Exceptions

No issue is reported when `StringBuilder` is:

- Accessed through `sb.CopyTo()`, `sb.GetChunks()`, `sb.Length`, or `sb[index]`.
- Passed as a method argument, on the grounds that it will likely be accessed through a `ToString()` invocation there.
- Passed in as a parameter to the current method, on the grounds that the callee will materialize the string.
- Retrieved by a custom function (`var sb = GetStringBuilder();`).
- Returned by the method.