Change the method name
MODIFY
plugin.xml
plugin.xml
<?xml version='1.0' encoding='utf-8'?>
-<plugin id="cordova-plugin-googlemaps" version="2.2.0-beta-20180127-0006" xmlns="http://apache.org/cordova/ns/plugins/1.0" xmlns:android="http://schemas.android.com/apk/res/android">
+<plugin id="cordova-plugin-googlemaps" version="2.2.0-beta-20180127-0009" xmlns="http://apache.org/cordova/ns/plugins/1.0" xmlns:android="http://schemas.android.com/apk/res/android">
<name>cordova-plugin-googlemaps</name>
<js-module name="BaseClass" src="www/BaseClass.js">
<runs />

MODIFY
www/KmlOverlay.js
www/KmlOverlay.js
@@ -251,7 +251,7 @@ KmlOverlay.prototype.getHashCode = function() {
KmlOverlay.prototype.getDefaultViewport = function() {
return this.camera;
};
-KmlOverlay.prototype.getMetadata = function() {
+KmlOverlay.prototype.getKmlData = function() {
return this.kmlData;
};
KmlOverlay.prototype.getMap = function() {

Change the method name