After this change all nodes that have a delimited-list are using the List API.
Let's look at a declaration with multiple declarators:
int a, b;
To generate a declarator list node we need to have the range of declarators: a, b. However, the ClangAST actually stores them as separate declarations:
int a ;
To solve that we mark the declarators on each separate declaration in the ClangAST and then for the final declarator int b, we shrink its range to fit to the already marked declarators.