title: Use ObjectId.GenerateNewId() or leave MongoDB to create one?
body: <p>In C# I can use the ObjectId.GenerateNewId() to generate ObjectId values.</p>
  
  <p>Most of the time when I insert a document in a collection I do not set the value of _id fields. MongoDB creates the ObjectId values automatically.</p>
  
  <p>I would like to ask if it is safe to set it manually by using the ObjectId.GenerateNewId() method.</p>