getResponseDataString is not the same as getResponseData

So I’m looking at the source of getResponseDataString, it is using a different buffer from getResponseData.

/**
 * Get the http response data.
 * @return std::vector<char>* the pointer that point to the _responseData.
 */
std::vector<char>* getResponseData()
{
    return &_responseData;
}

/**
 * Get the string pointer that point to the response data.
 * @return const char* the string pointer that point to the response data.
 */
const char* getResponseDataString() const
{
    return _responseDataString.c_str();
}

From the comments, it look like they should be returning from same buffer.

I can’t find anywhere in the code that is setting it. What is the serparate _responseDataString buffer used for?