private static String malformedHeaderNameMessage(AsciiString name) {
        final StringBuilder buf = new StringBuilder(IntMath.saturatedAdd(name.length(), 64));
        buf.append("malformed header name: ");

        final int nameLength = name.length();
        for (int i = 0; i < nameLength; i++) {
            final char ch = name.charAt(i);
            if (PROHIBITED_NAME_CHARS.get(ch)) {
                buf.append(PROHIBITED_NAME_CHAR_NAMES[ch]);
            } else {
                buf.append(ch);
            }
        }

        return buf.toString();
    }
Returned the raw header name used when creating the specified {@link AsciiString} with
{@link #create(String)}.
core/src/main/java/com/linecorp/armeria/common/HttpHeaderNames.java