[Custom Reports]: Make element_type and element_class_id optional in CsvCreationHandler

[markus-moser]

Problem

The custom report CSV export fails with:

The required options "element_class_id", "element_type" are missing.

CsvCreationHandler uses ExportCreationHandlerSetupTrait which marks element_type, element_class_id, and columns as required step config fields. This is correct for element grid exports (assets, data-objects), but the custom report flow reuses the same CsvCreationMessage / CsvCreationHandler without those fields — custom reports are not tied to any element type, so the collection step pre-builds all CSV data itself.

Fix

• Remove ExportCreationHandlerSetupTrait from CsvCreationHandler and override configureStep directly: only CONFIG_CONFIGURATION and CONFIG_COLUMNS remain required (with empty-array defaults); ELEMENT_TYPE and ELEMENT_CLASS_ID become optional with null defaults.
• Add extractOptionalConfigFieldFromJobStepConfig helper to AbstractHandler for safe extraction with a default value.
• Switch CsvCreationHandler to use the optional extractor for element_type and element_class_id.

The existing element-grid CSV export flow is unaffected — it still provides all fields, they are just no longer enforced at the step-config validation level.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

[codacy-production]

Not up to standards ⛔

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[martineiber]

LGTM