Select attribute automatically

Sometimes you only have 1 attribute value. 
Because
- this is the only way that the ERP system can do it or
- because it makes sense to point out this value to the customer or
- because there used to be several attributes and now there is only one 

An example of this is our own store :-) 

With this plugin, this single attribute is loaded automatically. 

As soon as there are several attributes, the customer has to select them manually again so that there are no incorrect purchases.