fix(module/subnet_sets): Change default value for nacl_associations variable

[piotr-rzepa]

Description

The change sets the default value for the nacl_associations variable from null to {} (an empty map).

Motivation and Context

Currently, the default null value causes Terraform's plan to fail in case no value for the variable is provided - the module (aws_network_acl_association resource) expects nacl_associations to be iterable (a map of strings), but when the user does not intend to associate any network ACLs with any subnet and skips the variable altogether, it throws an Invalid for_each argument error. The user has to explicitly set a nacl_associations variable to an empty map to avoid errors. By changing the default value from null to an empty map, the resource creation is skipped without any required workarounds from users.

How Has This Been Tested?

The subnet_sets module was deployed without setting any explicit value for nacl_associations variable. The plan and apply did not report any errors when the default value was set to an empty map.

Screenshots (if appropriate)

Error related to the nacl_associations being null:

Types of changes

• Bug fix (non-breaking change which fixes an issue)

Checklist

• [x] I have updated the documentation accordingly.
• [x] I have read the CONTRIBUTING document.
• [x] All new and existing tests passed.

[sebastianczech]

/validate paths="modules/subnet_set examples/combined_design"

Testing job ID: 6322173926 Job result: FAILURE

[pimielowski]

/validate paths="modules/subnet_set examples/combined_design"

Testing job ID: 6378065345 Job result: SUCCESS