private static void writeAscii(ByteBuf buf, int offset, CharSequence value, int valueLen) {
        if (value instanceof AsciiString) {
            ByteBufUtil.copy((AsciiString) value, 0, buf, offset, valueLen);
        } else {
            writeCharSequence(buf, offset, value, valueLen);
        }
    }
Appends the serialized {@link HttpHeaders} into the specifed {@link ByteBuf}.
grpc-protocol/src/main/java/com/linecorp/armeria/internal/common/grpc/protocol/GrpcTrailersUtil.java