title: Generate anonymous number for string property with AutoFixture
body: <p>I'm unit testing some mapping methods, and I have a source property of type string which is mapped to a destination property of type integer.</p>
  
  <p>So I would like AutoFixture to create the source object with an anonymous integer for the specific string property, not for all string properties.</p>
  
  <p>Is this possible?</p>