feat(dts-generator): add "explicit" flag for event parameter optionality

[akudev]

Previously, all properties in generated Xxx$YyyEventParameters interfaces were unconditionally forced to optional ("?"), regardless of their actual "optional" value in the api.json source data.

This adds support for an explicit boolean property on events. When an event has explicit: true, the generator respects each parameter property's actual optional value from the source NestedProperties data:

• optional: false → required (no ?)
• optional: true or undefined → optional (?)

Events without the flag (or with explicit: false) retain the existing behavior where all parameters are optional.

Changes:

• api-json.d.ts: Add explicit?: boolean to both ObjEvent and Ui5Event interfaces so the flag is recognized in the input type system.

• json-event-parameter-interfaces.ts: Extend buildProperties() to accept an explicit parameter. When true and a property has optional === false, override the forced optional back to false after addJsDocProps sets it. Pass event.explicit === true at the call site.

• json-fixer.ts: Add events to mapLikeProperties so that .dtsgenrc overlay merges can target individual events by name (matching how methods and properties overlays already work), enabling overlays like: { "name": "sap.m.Select", "events": [{ "name": "change", "explicit": true }] }

Needed for #529

[Copilot]

Pull request overview

Adds an explicit flag to the UI5 d.ts generator’s event model to optionally preserve required vs. optional event parameter properties from api.json (instead of forcing all event parameters to be optional), and enables overlays to target individual events.

Changes:

• Extend api.json typing (ObjEvent/Ui5Event) to accept explicit?: boolean.
• Update event-parameter interface generation to honor optional: false when event.explicit === true.
• Allow .dtsgenrc overlays to merge events by name (like methods/properties) and add snapshot-style tests for the explicit behavior.

Reviewed changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated 2 comments.

File	Description
test-packages/openui5-snapshot-test/test/explicit-event-params-spec.js	Adds tests validating optionality behavior with/without the explicit flag for different inheritance setups.
packages/dts-generator/src/utils/json-event-parameter-interfaces.ts	Implements explicit handling when building event parameter interface properties.
packages/dts-generator/src/types/api-json.d.ts	Adds explicit?: boolean to event type definitions so the flag is accepted by the input schema.
packages/dts-generator/src/phases/json-fixer.ts	Treats events as a map-like overlay property so overlays can merge events by name.

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