cast primitive type to nullable object

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C#

iv'e got a object witch i create out of an entity(T) using reflection , the object is my implementation of a table it holds a List of Columns witch i extract their properties from the entity using reflection :

public class Generic_Table<T> : Table
{

    ...// in ctor
    type = this.GetType().GetGenericArguments()[0]; // type of T
    BuildColumns(type);

    private void BuildColumns(Type type)
    {
        PropertyInfo[] properties = type.GetProperties();

        Columns = new KeyValuePair<string, Type>[properties.Count()];
        int i = 0;
        foreach (PropertyInfo property in properties)
        {
            Columns[i++] = new KeyValuePair<string, Type>(property.Name, property.PropertyType);
        }

    }

i'm looking for a way to cast the PropertyType value as a nullable type

so that the Type value in Columns[i] would be int? if for example some property as an int
PropertyType value.