public Builder addNestedType(
          int index, com.google.protobuf.DescriptorProtos.DescriptorProto value) {
        if (nestedTypeBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureNestedTypeIsMutable();
          nestedType_.add(index, value);
          onChanged();
        } else {
          nestedTypeBuilder_.addMessage(index, value);
        }
        return this;
      }