SqlAGDatabase: Add parameter to retain backup files

Details of the scenario you tried and the problem that is occurring

I am using SqlAGDatabase with the win_dsc module in Ansible in order to add the databases to the AG and its getting added as well but no .bak and .trn file is created at the mention backup path

The DSC configuration that is used to reproduce the issue (as detailed as possible)

 SqlAGDatabase 'TestAGDatabaseMemberships'
            {
                AvailabilityGroupName   = $Node.AvailabilityGroupName
                BackupPath              = '\\SQL1\AgInitialize'
                DatabaseName            = 'DB*', 'AdventureWorks'
                InstanceName            = $Node.InstanceName
                ServerName              = $Node.NodeName
                Ensure                  = 'Present'
                ProcessOnlyOnActiveNode = $true
                PsDscRunAsCredential    = $SqlAdministratorCredential
            }

But the above i am passing as below via Ansible
- name: Add Database to Always On Availability Group in "{{ groups['windows'][0] }}"
  when: inventory_hostname in groups['windows'][0]
  win_dsc:
       resource_name: SqlAGDatabase
       DatabaseName: D*, Test*
       ServerName: WINSER1
       InstanceName: MSSQLSERVER
       AvailabilityGroupName: TEST_AG
       BackupPath: \\WINSER1\backup_demo (shared network folder created in the winser1 server)
       Ensure: Present

SQL Server edition and version the target node is running

Microsoft SQL Server 2016 (SP2) (KB4052908) - 13.0.5026.0 (X64) 

SQL Server PowerShell modules present on the target node

Name      Version    Path
----      -------    ----
SqlServer 21.1.18147 C:\Program Files\WindowsPowerShell\Modules\SqlServer\21.1.18121\SqlServer.psd1
SQLPS     14.0       C:\Program Files (x86)\Microsoft SQL Server\130\Tools\PowerShell\Modules\SQLPS\SQLPS.psd1

The operating system the target node is running

OsName               : Microsoft Windows Server 2012 R2 Datacenter
OsOperatingSystemSKU : DatacenterServerEdition
OsArchitecture       : 64-bit
WindowsBuildLabEx    : 9600.17415.amd64fre.winblue_r4.141028-1500
OsLanguage           : en-US
OsMuiLanguages       : {en-US}

Version and build of PowerShell the target node is running

Name                           Value                                           
----                           -----                                           
PSVersion                      5.1.14409.1005                                  
PSEdition                      Desktop                                         
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}                         
BuildVersion                   10.0.14409.1005                                 
CLRVersion                     4.0.30319.42000                                 
WSManStackVersion              3.0                                             
PSRemotingProtocolVersion      2.3                                             
SerializationVersion           1.1.0.1

Version of the DSC module that was used ('dev' if using current dev branch)

Name         Version  Path                                                     
----         -------  ----                                                     
SqlServerDsc 12.4.0.0 C:\Program Files\WindowsPowerShell\Modules\SqlServerDsc\12.4.0.0\SqlServerDsc.psd1

Refer the screenshot below which shows that the Ansible run successful and it added the DB to the AG but no .bak and .trn file is create in \WINSER1\backup_demo

Start by locating the SqlAGDatabase resource and its BackupPath handling, then review how Always On database initialization creates or removes .bak and .trn files. Confirm the intended retention behavior for the new parameter against the reported Ansible scenario and SQL Server 2016 environment. Done means the parameter controls whether those backup files are retained as requested.