public Builder addVertices(org.bwapi.proxy.messages.BasicTypes.Position value) {
        if (verticesBuilder_ == null) {
          if (value == null) {
            throw new NullPointerException();
          }
          ensureVerticesIsMutable();
          vertices_.add(value);
          onChanged();
        } else {
          verticesBuilder_.addMessage(value);
        }
        return this;
      }