AAPT Error: attribute 'package' in <manifest> tag is not a valid Android package name

I have looked at the previous answers for this question but the AAPT error still occurs.

error: attribute 'package' in <manifest> tag is not a valid Android package name: 'org.emarti202.gcu.mpd-cw-em'.

Despite my applicationId in the build.gradle and the package names in the AndroidManifest.xml match, they still do not work. Is there a solution for this? Apologies is this is a simple fix, I cant seem to wrap my head around it.

AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="org.emarti202.gcu.mpd-cw-em">

    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION" />

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="MPD-CW-EM"
        android:roundIcon="@mipmap/ic_launcher_round"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">

        <meta-data android:name="com.google.android.geo.API_KEY"
            android:value="@string/map_key" />

        <activity android:name="org.emarti202.gcu.mpd-cw-em.MainActivity2"></activity>
        <activity android:name="org.emarti202.gcu.mpd-cw-em.MainActivity">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
</manifest>

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "org.emarti202.gcu.mpd-cw-em"
        minSdkVersion 23
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
}


dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    implementation 'com.android.support:design:28.0.0'
    implementation 'com.google.android.gms:play-services:+'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    // implementation 'com.alespero:expandable-cardview:0.6'
    // implementation 'com.google.android.gms:play-services-maps:16.1.0'
}

Unfortunately the hyphen '-' is not acceptable in a package name. Please reference this docs.

https://developer.android.com/guide/topics/manifest/manifest-element.html#package

A full Java-language-style package name for the Android app. The name may contain uppercase or lowercase letters ('A' through 'Z'), numbers, and underscores ('_'). However, individual package name parts may only start with letters. While building your app into the an application package (APK), the build system uses the package attribute for two things

Please change your package name to 'org.emarti202.gcu.mpd_cw_em'.