docs: public String setValue(String val) {
          String oldVal = this.val;
          if (parent != null) {
              oldVal = parent.get(this.key); // trust the container more
              int i = parent.indexOfKey(this.key);
              if (i != Attributes.NotFound)
                  parent.vals[i] = val;
          }
          this.val = val;
          return Attributes.checkNotNull(oldVal);
      }