How to set namespace when you create a new library or project?

Imagine that you want to create a new algorithms library.

For instance:

namespace Com.MyCompanyName.LibraryPathfinding 
{
//...
}

Another one could import this library (include namespace) and use it.

For instance:

using Com.MyCompanyName.LibraryPathfinding

namespace Com.YourCompanyName.ProjectX
{
//...
//ProjectX is a game
}

My question is:

If LibraryPathfinding use some kinds of util class which like "PriorityQueue", how to set PriorityQueue's namespace?

(1):

namespace Com.MyCompanyName.LibraryPathfinding.Collections
{
    public class PriorityQueue 
    {
       ////
    }
}

(2) :

namespace Com.MyCompanyName.Collections
{
     public class PriorityQueue
     {
       ////
     }
}

If choose (1), it means PriorityQueue is a part of LibraryPathfinding.

The advantage of this is:

LibraryPathfinding is completely independent.

If your project need pathfinding, just import "Com.MyCompanyName.LibraryPathfinding"

The disadvantage of this is:

Whenever your project need PriorityQueue, you must import "Com.MyCompanyName.LibraryPathfinding", even though ProjectX don't need Pathfinding.

For instance: In ProjectX, AIManager need a aggro list which use priority queue. But aggro list shouldn't dependent on Pathfinding!

If choose (2), it could resolve (1)'s problem.

The disadvantage of this is:

LibraryPathfinding will be not completely independent.

If you want to use LibraryPathfinding, you must import Com.MyCompanyName.Collections and Com.MyCompanyName.LibraryPathfinding. This means: you must release two libraries (to your user)!

Any advice would be very appreciated.

Thanks.