code: public Throwable getResolvingCause() {
          Throwable t = this, c = this;
          while (c instanceof ResolvingException) {
              t = c; c = t.getCause();
          }
          return c == null ? t : c;
      }
docs: Returns the underlying cause of this resolving exceptions.
  Unpacks nested resolving exceptions if necessary.
  @return cause