how get list of data of T variable

hi there

how to send a list of specific class to such method:

public static DataTable SetPropertyToDataTable(T dataList,Type _class) where T : class
{
Dictionary<string, object> columns = new Dictionary<string, object>();
var properties =_class.GetProperties();
foreach (var item in dataList)
foreach (var property in properties)
{
var name = property.Name;
var value = property.GetValue(item, null);
if(!columns.ContainsKey(name))
columns.Add(name, value);
}
return ImportPropertyAndValues(columns);
}

I mean T datalist