@Override
        public Boolean apply(Object left, Object right) {
          if (left instanceof String || right instanceof String) {
            return String.valueOf(left).equals(String.valueOf(right));
          }
          return Objects.equals(left, right);
        }
Built-in operations, functions and accessors.
Planned to be moved to import/implicit resolution
rather that inheritance.
generator/src/org/immutables/generator/Builtins.java