src/vs/editor/contrib/parameterHints/parameterHintsModel.ts/mergeTriggerContexts
function mergeTriggerContexts(previous: TriggerContext, current: TriggerContext) {
	switch (current.triggerKind) {
		case modes.SignatureHelpTriggerKind.Invoke:
			// Invoke overrides previous triggers.
			return current;

		case modes.SignatureHelpTriggerKind.ContentChange:
			// Ignore content changes triggers
			return previous;

		case modes.SignatureHelpTriggerKind.TriggerCharacter:
		default:
			return current;
	}
}