How does the Android build system find the dependancies?

I met with this error
Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
> Could not find com.google.firebase:firebase-core:11.8.1

It claimed to say that it looked in the folder file:/Users/bond/Library/Android/sdk/extras/m2repository/com/google/firebase/firebase-core/11.8.1/
and manually navigating to this folder yes, I could not see the firebase stuff.

I checked the SDK location base path in the project structure dialog under SDK location, and the base path is same as the
one shown in the error where system tried to look for firebase.

/Users/bond/Library/Android/sdk

Also, another project in the same system for the same version is not giving this error and I remember earlier 11.8 compiled.

when i checked, the build.gradle has below,

compile 'com.google.firebase:firebase-core:11.8.1'
    compile 'com.google.firebase:firebase-messaging:11.8.0'
    compile 'com.google.android.gms:play-services:11.8.0'


and changed to implementation like below which actually seems to have resolved issue with app but the module still gives the error

Error:(29, 20) Failed to resolve: com.google.firebase:firebase-core:11.8.1
Show in File
Show in Project Structure dialog

One blog post was suggesting to do this, which i already had.

allprojects {
  repositories {
    // ...
    maven { url "https://maven.google.com" }
  }
}




Error:Could not resolve all files for configuration ':app:debugRuntimeClasspath'.
> Could not find com.google.firebase:firebase-core:11.8.1.
  Searched in the following locations:
      file:/Users/bond/Library/Android/sdk/extras/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Users/bond/Library/Android/sdk/extras/google/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/google/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Users/bond/Library/Android/sdk/extras/android/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/android/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Applications/Android Studio.app/Contents/gradle/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Applications/Android Studio.app/Contents/gradle/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://jcenter.bintray.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://jcenter.bintray.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://maven.google.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://maven.google.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://jitpack.io/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://jitpack.io/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
  Required by:
      project :app
> Could not find com.google.firebase:firebase-core:11.8.1.
  Searched in the following locations:
      file:/Users/bond/Library/Android/sdk/extras/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Users/bond/Library/Android/sdk/extras/google/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/google/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Users/bond/Library/Android/sdk/extras/android/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Users/bond/Library/Android/sdk/extras/android/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      file:/Applications/Android Studio.app/Contents/gradle/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      file:/Applications/Android Studio.app/Contents/gradle/m2repository/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://dl.google.com/dl/android/maven2/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://jcenter.bintray.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://jcenter.bintray.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://maven.google.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://maven.google.com/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
      https://jitpack.io/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.pom
      https://jitpack.io/com/google/firebase/firebase-core/11.8.1/firebase-core-11.8.1.jar
  Required by:
      project :app > project :appynotifications