cordova-plugin-googlemaps: HtmlInfoWindow error: marker.getId is not a function

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plugin version: (check one with “x”) [ ] 1.4.x [x] 2.0.0-beta2

cordova information: (run $> cordova plugin list)

com.googlemaps.ios 2.3.0 "Google Maps SDK for iOS"
cordova-plugin-browsertab 0.2.0 "cordova-plugin-browsertab"
cordova-plugin-compat 1.0.0 "Compat"
cordova-plugin-console 1.0.5 "Console"
cordova-plugin-device 1.1.4 "Device"
cordova-plugin-geolocation 2.4.3 "Geolocation"
cordova-plugin-globalization 1.0.7 "Globalization"
cordova-plugin-googlemaps 2.0.0-beta2-20170731-1540 "cordova-plugin-googlemaps"
cordova-plugin-splashscreen 4.0.3 "Splashscreen"
cordova-plugin-statusbar 2.2.2 "StatusBar"
cordova-plugin-whitelist 1.3.1 "Whitelist"
cordova-sms-plugin 0.1.11 "Cordova SMS Plugin"
cordova-sqlite-storage 2.0.4 "Cordova sqlite storage plugin"
cordova.plugins.diagnostic 3.6.5 "Diagnostic"
ionic-plugin-keyboard 2.2.1 "Keyboard"

Current behavior: I add to the map many Marker. When I try to open the HtmlInfoWindow from a marker, I get this error : Unhandled Promise rejection: marker.getId is not a function ; Zone: <root> ; Task: null ; Value: TypeError: marker.getId is not a function

Related code, data or error log (please format your code or data):

loadMap() {
	...
	
	var htmlInfoWindow = new HtmlInfoWindow();
	htmlInfoWindow.setContent(`
		<div>test</div><br>
	`)

	this.map.one(GoogleMapsEvent.MAP_READY).then(() => {
			this.cameras.map(cam => {
				let latLng: LatLng = new LatLng(cam.position_y, cam.position_x);
				
				this.map.addMarker({
					position: latLng
				}).then((marker: Marker) => {
					marker.on(plugin.google.maps.event.MARKER_CLICK).subscribe(() => {
						htmlInfoWindow.open(marker);
					});
				})
			})
	});
}