private static void writeCharSequence(ByteBuf buf, int offset, CharSequence value, int valueLen) {
        for (int i = 0; i < valueLen; ++i) {
            buf.setByte(offset++, c2b(value.charAt(i)));
        }
    }
Appends the serialized {@link HttpHeaders} into the specifed {@link ByteBuf}.
grpc-protocol/src/main/java/com/linecorp/armeria/internal/common/grpc/protocol/GrpcTrailersUtil.java