anchor.diff:  Type rightType = GenericTypes.resolveType(Pair.class.getTypeParameters()[1], type);
   ----
   
  -The `GenericTypes.resolveType` method accepts a generic type parameter to
  -resolve, and a context type in which to resolve it.
  -
   In the first line, `Pair.class.getTypeParameters()[0]` gives the type variable
  -`L`. So if `type` was `Pair<Foo, Bar>`, the call to `resolveType` means "resolve
  -the type variable `L` in the context of `Pair<Foo, Bar>`, which resolves to the
  -left parameter, `Foo`.
  -
  -Likewise in the second line, `Pair.class.getTypeParameters()[0]` gives the type
  -variable `L`, so the `resolveType` call returns `Bar`.
  +`L`. Likewise in the second line, `Pair.class.getTypeParameters()[1]` gives the type
  +variable `R`.
  +
  +We use `resolveType()` to resolve the types for the `L` and `R` type variables
  +in the context of the mapped type.
   
   Now that we have the types for `L` and `R`, we can look up the column mappers
   for those types from the `ColumnMappers` config class, through the config
  
positive.code: the current column mapper configuration.
  
  Next we call `ColumnMappers.findFor()` to get the column mappers for the left
  and right type parameters.
  
  [TIP]
  You may have noticed that although this method can return `Optional`, we're
  
negative.code: }
  ----
  
  [TIP]
  The `GenericType` utility class is discussed in <<Working with Generic Types>>.
  
  ==== Column Mappers
  
  