public boolean isActivityVisible() {
        return isActivityVisible;
    }
Generic View Model class for {@link ConfigurationServerActivity},{@link ConfigurationClientActivity},
{@link GenericOnOffServerActivity}, {@link GenericLevelServerActivity}, {@link VendorModelActivity},
{@link GenericModelConfigurationActivity}
app/src/main/java/no/nordicsemi/android/nrfmesh/viewmodels/ModelConfigurationViewModel.java