INTEXT-73 Sending multipart SMS messages through a SMPP provider using sar_msg_ref_num, sar_segment_seqnum and sar_total_segments

This replaces PR https://github.com/spring-projects/spring-integration-extensions/pull/50
Why isn't enough `new LinkedList<String>()` instead of `new String[]` ?
I mean there there is no reason to get deal with arrays.