the class MongoCollectionStringBuidler has a bug.
if remove any connection string parameter by Remove method, the value still remains in it's property.
for example:
var builder = new MongoConnectionStringBuilder()
builder.UserName = "abc";//The user name must be abc
builder.Remove("username");//The user name must be null
string username = builder.UserName;//The user name still is abc

Reporter: Sean.Wood
E-mail: dexiang.wu@gamil.com