def _get_default_headers(
    user_agent,
    content_type="application/json; charset=UTF-8",
    x_upload_content_type=None,
):
    """Get the headers for a request.

    Args:
        user_agent (str): The user-agent for requests.
    Returns:
        Dict: The headers to be used for the request.
    """
    return {
        "Accept": "application/json",
        "Accept-Encoding": "gzip, deflate",
        "User-Agent": user_agent,
        "x-goog-api-client": user_agent,
        "content-type": content_type,
        "x-upload-content-type": x_upload_content_type or content_type,
    }