Dependency issue when linking app to Firebase Crashlytics - maven/android/flutter - firebase

Question

I am trying to set up Firebase crashlytics to my flutter app. I have followed the steps from https://blog.codemagic.io/practical-guide-flutter-firebase-codemagic/ and works fine when I run in local. However, I see a failure using the CI/CD tool - Codemagic.
== Initializing Gradle project /Users/builder/clone/android/app/build.gradle ==
Picked up _JAVA_OPTIONS: -Xmx3g
FAILURE: Build failed with an exception.
Where:
Build file '/Users/builder/clone/android/build.gradle' line: 7
What went wrong:
A problem occurred evaluating root project 'android'.
Could not find method maven() for arguments [build_8np9gq8hl982yq6pq0eovgcan$_run_closure1$_closure3#6b63e6ad] on object of type org.gradle.api.internal.initialization.DefaultScriptHandler.
Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.
Not sure of any solution. Reached out to codemagic support on slack!
This is now my app/android/build.gradle file looked like:
buildscript {
repositories {
google()
jcenter()
}
maven {
url 'https://maven.fabric.io/public'
}
dependencies {
classpath 'com.android.tools.build:gradle:3.3.0'
classpath 'com.google.gms:google-services:4.2.0'
classpath 'io.fabric.tools:gradle:1.26.1'
}
}
allprojects {
repositories {
google()
jcenter()
}
}
rootProject.buildDir = '../build'
subprojects {
project.buildDir = "${rootProject.buildDir}/${project.name}"
}
subprojects {
project.evaluationDependsOn(':app')
}
task clean(type: Delete) {
delete rootProject.buildDir
}
Expected result: The build should happen fine on codemagic

Answer 1

With support from Mikhail at code magic, below is the solution:
maven should be inside repositories
https://docs.gradle.org/current/userguide/declaring_repositories.html#sec:declaring_custom_repository
Like below:
repositories {
google()
jcenter()
maven {
url 'https://maven.fabric.io/public'
}
}
dependencies {
classpath 'com.android.tools.build:gradle:3.3.0'
classpath 'com.google.gms:google-services:4.2.0'
classpath 'io.fabric.tools:gradle:1.26.1'
}