Fix updates on empty env vars in aws_lambda_func

[nam054]

Description

Resource wanted to repeatedly apply a change on an empty environment.variables. Now it will check that the variable is not empty before flattening.

Relations

Closes #29255

References

Output from Acceptance Testing

> make testacc TESTARGS='-run=TestAccLambdaFunction_' PKG=lambda
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/lambda/... -v -count 1 -parallel 20  -run=TestAccLambdaFunction_ -timeout 180m
=== RUN   TestAccLambdaFunction_basic
.......
--- PASS: TestAccLambdaFunction_VPCPublishHas_changes (2135.68s)
--- PASS: TestAccLambdaFunction_disappears (464.75s)
--- PASS: TestAccLambdaFunction_LocalUpdate_nameOnly (635.94s)
--- PASS: TestAccLambdaFunction_localUpdate (572.40s)
--- PASS: TestAccLambdaFunction_unpublishedCodeUpdate (538.12s)
--- PASS: TestAccLambdaFunction_VPC_replaceSGWithCustom (516.01s)
--- PASS: TestAccLambdaFunction_fileSystem (2193.61s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/lambda     2196.658s
...

[github-actions]

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[github-actions]

Hey @nam054 👋 Thank you very much for your contribution! At times, our maintainers need to make direct edits to pull requests in order to help get it ready to be merged. Your current settings do not allow maintainers to make such edits. To help facilitate this, update your pull request to allow such edits as described in GitHub's Allowing changes to a pull request branch created from a fork documentation. (If you're using a fork owned by an organization, your organization may not allow you to change this setting. If that is the case, let us know.)

[jar-b]

LGTM 🎉

$ make testacc PKG=lambda TESTS=TestAccLambdaFunction_
==> Checking that code complies with gofmt requirements...
TF_ACC=1 go test ./internal/service/lambda/... -v -count 1 -parallel 20 -run='TestAccLambdaFunction_'  -timeout 180m
--- PASS: TestAccLambdaFunction_nameValidation (3.90s)
=== CONT  TestAccLambdaFunction_versionedUpdate
--- PASS: TestAccLambdaFunction_Zip_validation (7.98s)
=== CONT  TestAccLambdaFunction_versioned
--- PASS: TestAccLambdaFunction_skipDestroy (47.52s)
=== CONT  TestAccLambdaFunction_architecturesUpdate
--- PASS: TestAccLambdaFunction_snapStart (61.49s)
=== CONT  TestAccLambdaFunction_concurrencyCycle
--- PASS: TestAccLambdaFunction_basic (74.14s)
=== CONT  TestAccLambdaFunction_encryptedEnvVariables
--- PASS: TestAccLambdaFunction_ephemeralStorage (80.49s)
=== CONT  TestAccLambdaFunction_EnvironmentVariables_emptyUpgrade
--- PASS: TestAccLambdaFunction_enablePublish (80.99s)
=== CONT  TestAccLambdaFunction_EnvironmentVariables_noValue
--- PASS: TestAccLambdaFunction_disablePublish (94.89s)
=== CONT  TestAccLambdaFunction_envVariables
--- PASS: TestAccLambdaFunction_architectures (99.75s)
=== CONT  TestAccLambdaFunction_expectFilenameAndS3Attributes
--- PASS: TestAccLambdaFunction_expectFilenameAndS3Attributes (0.85s)
=== CONT  TestAccLambdaFunction_emptyVPC
--- PASS: TestAccLambdaFunction_deadLetter (118.63s)
=== CONT  TestAccLambdaFunction_s3
=== CONT  TestAccLambdaFunction_nilDeadLetter
--- PASS: TestAccLambdaFunction_deadLetterUpdated (124.04s)
--- PASS: TestAccLambdaFunction_s3 (32.76s)
=== CONT  TestAccLambdaFunction_VPC_replaceSGWithCustom
--- PASS: TestAccLambdaFunction_EnvironmentVariables_emptyUpgrade (77.24s)
=== CONT  TestAccLambdaFunction_VPC_properIAMDependencies
--- PASS: TestAccLambdaFunction_versioned (296.41s)
=== CONT  TestAccLambdaFunction_fileSystem
--- PASS: TestAccLambdaFunction_runtimes (340.86s)
=== CONT  TestAccLambdaFunction_VPCPublishHas_changes
--- PASS: TestAccLambdaFunction_vpcRemoval (708.37s)
=== CONT  TestAccLambdaFunction_S3Update_basic
--- PASS: TestAccLambdaFunction_S3Update_basic (54.92s)
=== CONT  TestAccLambdaFunction_S3Update_unversioned
--- PASS: TestAccLambdaFunction_S3Update_unversioned (53.97s)
=== CONT  TestAccLambdaFunction_tracing
--- PASS: TestAccLambdaFunction_localUpdate (1275.73s)
=== CONT  TestAccLambdaFunction_LocalUpdate_nameOnly
--- PASS: TestAccLambdaFunction_EnvironmentVariables_noValue (1225.47s)
=== CONT  TestAccLambdaFunction_layersUpdate
--- PASS: TestAccLambdaFunction_nilDeadLetter (1191.59s)
=== CONT  TestAccLambdaFunction_unpublishedCodeUpdate
--- PASS: TestAccLambdaFunction_concurrencyCycle (1257.54s)
=== CONT  TestAccLambdaFunction_concurrency
--- PASS: TestAccLambdaFunction_emptyVPC (1224.18s)
=== CONT  TestAccLambdaFunction_codeSigning
--- PASS: TestAccLambdaFunction_versionedUpdate (1327.55s)
=== CONT  TestAccLambdaFunction_tags
--- PASS: TestAccLambdaFunction_encryptedEnvVariables (1263.12s)
=== CONT  TestAccLambdaFunction_disappears
--- PASS: TestAccLambdaFunction_envVariables (1278.81s)
=== CONT  TestAccLambdaFunction_layers
--- PASS: TestAccLambdaFunction_VPC_replaceSGWithDefault (1394.46s)
=== CONT  TestAccLambdaFunction_KMSKeyARN_noEnvironmentVariables
--- PASS: TestAccLambdaFunction_VPC_withInvocation (1493.96s)
--- PASS: TestAccLambdaFunction_vpcUpdate (1497.78s)
--- PASS: TestAccLambdaFunction_VPC_replaceSGWithCustom (1395.76s)
--- PASS: TestAccLambdaFunction_vpc (1880.16s)
--- PASS: TestAccLambdaFunction_architecturesWithLayer (2108.81s)
--- PASS: TestAccLambdaFunction_tracing (1301.01s)
--- PASS: TestAccLambdaFunction_architecturesUpdate (2072.89s)
--- PASS: TestAccLambdaFunction_layersUpdate (849.67s)
--- PASS: TestAccLambdaFunction_concurrency (839.22s)
--- PASS: TestAccLambdaFunction_disappears (826.19s)
--- PASS: TestAccLambdaFunction_layers (798.48s)
--- PASS: TestAccLambdaFunction_codeSigning (849.12s)
--- PASS: TestAccLambdaFunction_LocalUpdate_nameOnly (902.67s)
--- PASS: TestAccLambdaFunction_KMSKeyARN_noEnvironmentVariables (783.95s)
--- PASS: TestAccLambdaFunction_tags (853.22s)
--- PASS: TestAccLambdaFunction_unpublishedCodeUpdate (874.15s)
--- PASS: TestAccLambdaFunction_VPCPublishNo_changes (2266.77s)
--- PASS: TestAccLambdaFunction_VPCPublishHas_changes (1927.76s)
--- PASS: TestAccLambdaFunction_fileSystem (2472.00s)
--- PASS: TestAccLambdaFunction_VPC_properIAMDependencies (2648.74s)
PASS
ok      github.com/hashicorp/terraform-provider-aws/internal/service/lambda     2809.493s

[github-actions]

This functionality has been released in v4.59.0 of the Terraform AWS Provider. Please see the Terraform documentation on provider versioning or reach out if you need any assistance upgrading.

For further feature requests or bug reports with this functionality, please create a new GitHub issue following the template. Thank you!

[github-actions]

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If you have found a problem that seems related to this change, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.