V3196. Parameter is not utilized inside the method body, but an identifier with a similar name is used inside the same method.

The analyzer has detected a suspicious code fragment where one of the parameters is not in use. At the same time, the value of a similarly named variable, field, or property is used in the method/constructor body. The value may have been mistakenly used instead of the parameter value of the method.

Let's look at the example:

public GridAnswerData(int questionId, ....)
{
  this.QuestionId = QuestionId;
  ....
}

In this constructor, the property is assigned its own value. This is obviously a typo, and the value of the 'questionId' parameter should be assigned to the 'this.QuestionId' property. So, you can resolve the issue this way:

public GridAnswerData(int questionId, ....)
{
    this.QuestionId = questionId;
    ....
}

Take a look at another example:

public async void Save(string filePath = null)
{
  using(var writer = new StreamWriter(FilePath))
  {
    ....
    await writer.WriteAsync(Data);
  }
}

In this case, the path to the file where some data should be saved is passed to the 'Save' method as the 'filePath' argument. However, the save is done to another file instead, the path to which is returned by the 'FilePath' property. We can assume that the 'FilePath' property should be used only when the 'filePath' argument is set to 'null'. The fixed code may look as follows:

public async void Save(string filePath = null)
{
  var path = filePath ?? FilePath;
  using(var writer = new StreamWriter(path))
  {
    ....
    await writer.WriteAsync(Data);
  }
}

Even if this assumption is incorrect, an unused parameter in a method signature can be confusing. It may also lead to errors when you use this method in the future.