fix: [SDK-5332] reject blank identity strings

[abdulraqeeb33]

Description

One Line Summary

Reject null and empty identity strings through one shared helper.

Details

Motivation

Fixes SDK-5332.

Empty login was forwarded to the native channel. Null and empty are rejected together on the identity APIs below. Part of SDK-5327.

Scope

rejectNullOrEmpty in lib/src/utils.dart rejects null and empty for:

• initialize(appId)
• login(externalId)
• addAlias / addAliases (label and id)
• removeAlias / removeAliases
• addEmail / removeEmail
• addSms / removeSms
• addTag / addTags (key only). An empty tag value is allowed. A null tag value is rejected.
• removeTag / removeTags
• addTrigger / addTriggers (key only). An empty trigger value is allowed.
• removeTrigger / removeTriggers
• trackEvent(name)

Whitespace is still allowed. Public method signatures are unchanged.

setLanguage("") is not rejected. It is the reset to the device language, and there is no other reset path. The Dart parameter is a non-null String, so null cannot reach this method.

Testing

Unit testing

flutter test for onesignalflutter_test.dart and user_test.dart passed, including login("") leaving the channel external id unset. flutter analyze lib test reported no issues.

Manual testing

Not run. The guards return before the method channel call, and the unit tests assert the mock channel is not invoked.

Affected code checklist

• Notifications
  • Display
  • Open
  • Push Processing
  • Confirm Deliveries
• Outcomes
• Sessions
• In-App Messaging
• REST API requests
• Public API changes

Checklist

Overview

• I have filled out all REQUIRED sections above
• PR does one thing
• Any Public API changes are explained in the PR details and conform to existing APIs

Testing

• I have included test coverage for these changes, or explained why they are not needed
• All automated tests pass, or I explained why that is not possible
• I have personally tested this on my device, or explained why that is not possible

Final pass

• Code is as readable as possible.
• I have reviewed this PR myself, ensuring it meets each checklist item