Keep unsent messages when the session is reset by its schedule

[aymenjam]

Problem

When the app sends a message while the session is not logged on (for example outside the session time), the message is saved in the message store. Then the session is reset by its schedule, and the reset deletes the store. So the message is never sent.

This does not match the Javadoc of Application.onCreate(): "If no one is logged on, the messages will be sent at the time a connection is established with the counterparty."

Closes #986
Refs #463

Solution

This PR adds a new session setting: KeepUnsentMessagesOnReset (default N).

With KeepUnsentMessagesOnReset=Y:

• When a message is saved but not sent, the store keeps the sequence number of the first unsent message.
• When the session is reset by its schedule, the unsent application messages are copied into the new store, with new sequence numbers.
• After the next logon, they are sent again with PossDupFlag=Y when the counterparty asks for them (ResendRequest).
• The value is cleared after a successful logon.

The value is saved in the store, so it works after a restart.

As discussed in #986:

• MessageStore has two new default methods: getFirstUnsentSenderMsgSeqNum() and setFirstUnsentSenderMsgSeqNum(int). By default they do nothing (get returns -1), so custom stores still compile and work as before.
• The value is saved in a separate file or table:
  • MemoryStore: in memory.
  • FileStore and CachedFileStore: new file <session>.firstunsentseqnum.
  • JdbcStore: new table unsent_seqnums. The name can be changed with JdbcStoreUnsentSeqNumsTableName. The table is optional. Without it, JdbcStore works as before.
• The SQL scripts for HSQLDB, MySQL, MSSQL, Oracle and PostgreSQL create the new table.

If the store does not support it, or if PersistMessages=N, the session logs a warning and works as before.

Messages are still lost with ResetOnLogon, ResetOnLogout, ResetOnDisconnect, a Logon with ResetSeqNumFlag=Y, or a call to Session.reset(). These resets are asked by the user or by the counterparty, so this PR does not change them.

Open question

The default is N, so nothing changes for current users. In #986 we did not decide if it should be Y by default. I am happy to change it.

Tests

• SessionTest: unsent messages are kept after a scheduled reset, resent after logon, and kept after a restart; messages that were already sent are not kept; no change when the setting is off.
• DefaultSessionFactoryTest: the new setting is read.
• AbstractMessageStoreTest: get, set, refresh and reset of the new value. It runs for MemoryStore, FileStore, CachedFileStore and JdbcStore (also the legacy table layout).
• JdbcStoreTest: JdbcStore works without the new table.

[codecov]

Codecov Report

❌ Patch coverage is 91.71975% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 71.20%. Comparing base (149869e) to head (d7444bf).

Files with missing lines	Patch %	Lines
quickfixj-core/src/main/java/quickfix/Session.java	86.56%	6 Missing and 3 partials ⚠️
...ickfixj-core/src/main/java/quickfix/JdbcStore.java	96.07%	2 Missing ⚠️
...uickfixj-core/src/main/java/quickfix/JdbcUtil.java	80.00%	0 Missing and 1 partial ⚠️
...fixj-core/src/main/java/quickfix/MessageStore.java	50.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #1345      +/-   ##
============================================
+ Coverage     70.79%   71.20%   +0.41%     
- Complexity     2270     2324      +54     
============================================
  Files           161      162       +1     
  Lines          9077     9231     +154     
  Branches       1192     1213      +21     
============================================
+ Hits           6426     6573     +147     
- Misses         2198     2204       +6     
- Partials        453      454       +1     

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