WW-5451 Fixes NPE when iterator starts with null

[lukaszlenart]

PR fixes NPE

ERROR org.apache.struts2.dispatcher.DefaultDispatcherErrorHandler - Exception occurred during processing request: null
java.lang.NullPointerException: null
    at org.apache.struts2.components.IteratorComponent.start(IteratorComponent.java:309) ~[struts2-core-6.4.0.jar:6.4.0]
...

Fixes WW-5451

[kusalk]

NIce catch

[sonarcloud]

Quality Gate failed

Failed conditions
10 Security Hotspots
31.0% Coverage on New Code (required ≥ 80%)
3.9% Duplication on New Code (required ≤ 3%)
E Security Rating on New Code (required ≥ A)
E Reliability Rating on New Code (required ≥ A)

See analysis details on SonarCloud

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