Cleanup root build files (#6606)

Per [b/384956859](https://b.corp.google.com/issues/384956859),

This migrates all of our root build files to `kts`. It also refactors
our usages to be more inline with modern gradle practices.

Furthermore, this PR also fixes the following:

- [b/384956861](https://b.corp.google.com/issues/384956861) -> Provide
fallback for build script names

build.gradle.kts

@@ -0,0 +1,71 @@
+/*
+ * Copyright 2024 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import com.diffplug.gradle.spotless.SpotlessPlugin
+import java.util.regex.Pattern
+
+plugins {
+  alias(libs.plugins.spotless)
+  alias(libs.plugins.protobuf) apply false
+  alias(libs.plugins.errorprone)
+  alias(libs.plugins.crashlytics) apply false
+  id("PublishingPlugin")
+  id("firebase-ci")
+  id("smoke-tests")
+  alias(libs.plugins.google.services)
+}
+
+extra["targetSdkVersion"] = 34
+
+extra["compileSdkVersion"] = 34
+
+extra["minSdkVersion"] = 21
+
+firebaseContinuousIntegration {
+  ignorePaths =
+    listOf(
+      Pattern.compile(".*\\.gitignore$"),
+      Pattern.compile(".*\\/.*.md$"),
+      Pattern.compile(".*\\.gitignore$"),
+    )
+}
+
+fun Project.applySpotless() {
+  apply<SpotlessPlugin>()
+  spotless {
+    java {
+      target("src/**/*.java")
+      targetExclude("**/test/resources/**")
+      googleJavaFormat("1.22.0").reorderImports(true).skipJavadocFormatting()
+    }
+    kotlin {
+      target("src/**/*.kt")
+      ktfmt("0.41").googleStyle()
+    }
+    kotlinGradle {
+      target("*.gradle.kts") // default target for kotlinGradle
+      ktfmt("0.41").googleStyle()
+    }
+  }
+}
+
+applySpotless()
+
+configure(subprojects) { applySpotless() }
+
+tasks.named("clean") { delete(rootProject.layout.buildDirectory) }
+
+apply(from = "gradle/errorProne.gradle")

buildSrc/build.gradle.kts

@@ -74,9 +74,13 @@ gradlePlugin {
             id = "LicenseResolverPlugin"
             implementationClass = "com.google.firebase.gradle.plugins.license.LicenseResolverPlugin"
         }
-        register("multiProjectReleasePlugin") {
-            id = "MultiProjectReleasePlugin"
-            implementationClass = "com.google.firebase.gradle.MultiProjectReleasePlugin"
+        register("continuousIntegrationPlugin") {
+            id = "firebase-ci"
+            implementationClass = "com.google.firebase.gradle.plugins.ci.ContinuousIntegrationPlugin"
+        }
+        register("smokeTestsPlugin") {
+            id = "smoke-tests"
+            implementationClass = "com.google.firebase.gradle.plugins.ci.SmokeTestsPlugin"
         }
         register("publishingPlugin") {
             id = "PublishingPlugin"

gradle/libs.versions.toml

@@ -114,12 +114,9 @@ findbugs-jsr305 = { module = "com.google.code.findbugs:jsr305", version = "3.0.2
 firebase-appdistribution-gradle = { module = "com.google.firebase:firebase-appdistribution-gradle", version.ref = "firebaseAppdistributionGradle" }
 firebase-common = { module = "com.google.firebase:firebase-common", version.ref = "firebaseCommon" }
 firebase-components = { module = "com.google.firebase:firebase-components", version.ref = "firebaseComponents" }
-firebase-crashlytics-gradle = { module = "com.google.firebase:firebase-crashlytics-gradle", version.ref = "firebaseCrashlyticsGradle" }
 glide = { module = "com.github.bumptech.glide:glide", version.ref = "glide" }
 google-api-client = { module = "com.google.api-client:google-api-client", version.ref = "googleApiClient" }
 google-dexmaker = { module = "com.google.dexmaker:dexmaker", version.ref = "dexmakerVersion" }
-google-services = { module = "com.google.gms:google-services", version.ref = "googleServices" }
-gradle-errorprone-plugin = { module = "net.ltgt.gradle:gradle-errorprone-plugin", version.ref = "gradleErrorpronePlugin" }
 grpc-android = { module = "io.grpc:grpc-android", version.ref = "grpc" }
 grpc-kotlin-stub = { module = "io.grpc:grpc-kotlin-stub", version.ref = "grpcKotlin" }
 grpc-okhttp = { module = "io.grpc:grpc-okhttp", version.ref = "grpc" }
@@ -173,7 +170,6 @@ playservices-base = { module = "com.google.android.gms:play-services-base", vers
 playservices-basement = { module = "com.google.android.gms:play-services-basement", version = "18.3.0" }
 playservices-tasks = { module = "com.google.android.gms:play-services-tasks", version = "18.1.0" }
 proto-google-common-protos = { module = "com.google.api.grpc:proto-google-common-protos", version.ref = "protoGoogleCommonProtos" }
-protobuf-gradle-plugin = { module = "com.google.protobuf:protobuf-gradle-plugin", version.ref = "protobufGradlePlugin" }
 protobuf-java = { module = "com.google.protobuf:protobuf-java", version.ref = "javalite" }
 protobuf-java-lite = { module = "com.google.protobuf:protobuf-javalite", version.ref = "javalite" }
 protobuf-kotlin-lite = { module = "com.google.protobuf:protobuf-kotlin-lite", version.ref = "javalite" }
@@ -235,3 +231,7 @@ maven-resolver = [
 kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }
 kotlinx-serialization = { id = "org.jetbrains.kotlin.plugin.serialization", version.ref = "serialization-plugin" }
 spotless = { id = "com.diffplug.spotless", version.ref = "spotless" }
+protobuf = { id = "com.google.protobuf", version.ref = "protobufGradlePlugin" }
+errorprone = { id = "net.ltgt.errorprone", version.ref = "gradleErrorpronePlugin" }
+google-services = { id = "com.google.gms.google-services", version.ref = "googleServices" }
+crashlytics = { id = "com.google.firebase.crashlytics", version.ref = "firebaseCrashlyticsGradle" }

health-metrics/apk-size/apk-size.gradle

@@ -28,8 +28,6 @@ plugins {
     id "com.dorongold.task-tree" version "3.0.0"
 }
 
-apply from: '../../sdkProperties.gradle'
-
 task clean(type: Delete) {
     delete rootProject.buildDir
 }

health-metrics/apk-size/app/default.gradle

@@ -29,7 +29,7 @@ android {
 
     defaultConfig {
         applicationId 'com.google.apksize'
-        minSdkVersion project.targetSdkVersion
+        minSdkVersion 34
         multiDexEnabled true
         targetSdkVersion 33
         versionCode 1