src/vs/editor/contrib/parameterHints/parameterHintsModel.ts/ParameterHintsModel/onModelChanged
class ParameterHintsModel:	private onModelChanged(): void {
		this.cancel();

		// Update trigger characters
		this.triggerChars = new CharacterSet();
		this.retriggerChars = new CharacterSet();

		const model = this.editor.getModel();
		if (!model) {
			return;
		}

		for (const support of modes.SignatureHelpProviderRegistry.ordered(model)) {
			for (const ch of support.signatureHelpTriggerCharacters || []) {
				this.triggerChars.add(ch.charCodeAt(0));

				// All trigger characters are also considered retrigger characters
				this.retriggerChars.add(ch.charCodeAt(0));
			}

			for (const ch of support.signatureHelpRetriggerCharacters || []) {
				this.retriggerChars.add(ch.charCodeAt(0));
			}
		}
	}