> What does "coordinates" mean here?

Suppose we have a ```BuiltInMethod``` signature that looks like:
```Map<JAXBElement<T1>, JAXBElement<T2>> convertToSomething(Map<T1, T2> source)```, then
1) Take in mind that the ```MapperCreationProcessor``` has the responsibility to do matching.
2) ```MapperCreationProcessor``` has the knowledge what the actual types of generic type variables ```T1``` and ```T2``` actually are
3) The ```BuiltIn``` implementation (e.g. ```ListOfValueToListOfJaxbElem```) has the knowledge what kind of mappers are needed and to which generic type variables they apply that it needs to generate the adapter (wrapper), or perhaps the method itself

So, I needed a mechanism that tells the ```MapperCreationProcessor``` the location of the generic type variables on the return type respectively on the parameter(s) for which a method should be searched. 

I reckon it could use some more explanation.. :)