Inspector support for .json TextAsset

I want to use .json files to define certain attributes for objects. For instance, "spider.json" or "wolf.json" files.

I want to be able to assign those files to specific Game Objects through the Unity editor and to be able to choose a different one through the Editor itself.

Basically, I would have a class such as:

 public class Unit: MonoBehaviour {
     public TextAsset jsonFile;
 }

Then, in the Editor itself, I would in principle be able to choose a text asset to assign to jsonFile.

However, .json files don't seem to appear in the inspector. I have renamed it to .txt and those do appear, but I don't really like the idea of having to use .txt for .json files.

According to the docs (http://docs.unity3d.com/Manual/class-TextAsset.html) both .txt and .json files (among others) are supported as TextAssets.

Am I doing something wrong; is that the expected behaviour of the inspector?

Would there be any other way to give designers the ability to choose a file (such as a .json, in this case) through the Editor, to link it to an object?