refactor out the if

Author: David Motsonashvili

plugins/src/main/java/com/google/firebase/gradle/plugins/CopyGoogleServicesPlugin.kt

@@ -37,12 +37,12 @@ import org.gradle.kotlin.dsl.register
  */
 abstract class CopyGoogleServicesPlugin : Plugin<Project> {
   override fun apply(project: Project) {
-    val sourcePath = getSourcePath(project)
-    if (sourcePath == null) {
+    if (File(project.projectDir, "google-services.json").exists()) {
       project.logger.warn("Google Services file already present in project, skipping copy task")
       return
     }
 
+    val sourcePath = getSourcePath(project)
     val copyRootGoogleServices = registerCopyRootGoogleServicesTask(project, sourcePath)
 
     project.allprojects {
@@ -99,12 +99,9 @@ abstract class CopyGoogleServicesPlugin : Plugin<Project> {
     return !file.readText().contains(targetPackageLine)
   }
 
-  private fun getSourcePath(project: Project): String? {
+  private fun getSourcePath(project: Project): String {
     val path =
       System.getenv("FIREBASE_GOOGLE_SERVICES_PATH") ?: "${project.rootDir}/google-services.json"
-    if (File(project.projectDir, "google-services.json").exists()) {
-      return null
-    }
     if (File(path).exists()) {
       return path
     }