Use google mirror first.

Author: shunping

buildSrc/src/main/groovy/org/apache/beam/gradle/Repositories.groovy

@@ -36,8 +36,8 @@ class Repositories {
         return
       }
 
-      mavenCentral()
       maven { url "https://maven-central.storage-download.googleapis.com/maven2/" }
+      mavenCentral()
       mavenLocal()
 
       // For Confluent Kafka dependencies
@@ -69,8 +69,8 @@ class Repositories {
     project.offlineDependencies {
       repositories {
         mavenLocal()
-        mavenCentral()
         maven { url "https://maven-central.storage-download.googleapis.com/maven2/" }
+        mavenCentral()
         maven { url "https://plugins.gradle.org/m2/" }
         maven { url "https://repo.spring.io/plugins-release" }
         maven { url "https://packages.confluent.io/maven/" }