@FormatMethod
    static HttpData ofAscii(@FormatString String format, Object... args) {
        return of(StandardCharsets.US_ASCII, format, args);
    }
Converts the specified formatted string into a US-ASCII {@link HttpData}. The string is formatted by
{@link String#format(Locale, String, Object...)} with {@linkplain Locale#ENGLISH English locale}.

@param format {@linkplain Formatter the format string} of the response content
@param args the arguments referenced by the format specifiers in the format string

@return a new {@link HttpData}. {@link #empty()} if {@code format} is empty.
core/src/main/java/com/linecorp/armeria/common/HttpData.java