code: public int setRecursionLimit(final int limit) {
      if (limit < 0) {
        throw new IllegalArgumentException(
          "Recursion limit cannot be negative: " + limit);
      }
      final int oldLimit = recursionLimit;
      recursionLimit = limit;
      return oldLimit;
    }
docs: Set the maximum message recursion depth.  In order to prevent malicious
  messages from causing stack overflows, {@code CodedInputStream} limits
  how deeply messages may be nested.  The default limit is 64.
  
  @return the old limit.