pub fn set_request_header_if_absent<V>(
    request: Builder,
    key: HeaderName,
    value: V,
) -> BuilderExpand description
Given an HTTP request, set a request header if that header was not already set.
pub fn set_request_header_if_absent<V>(
    request: Builder,
    key: HeaderName,
    value: V,
) -> BuilderGiven an HTTP request, set a request header if that header was not already set.