fix: update gradlePluginPortal workaround for JCenter availability is…

…sue (#3861)

* Fixing workaround from #3784 which modified metadata sources in build.gradle's subprojects.repositories block, when it should have been made in settings.gradle's pluginManagement.repositories block instead.

* This changes dependency resolution to deprioritize gradle plugin portal (with JCenter workaround) in favour of maven central, given the latest availability issues encountered.

build.gradle

@@ -70,13 +70,7 @@ subprojects {
   group 'com.google.cloud.tools'
 
   repositories {
-    mavenCentral {
-      metadataSources {
-        mavenPom()
-        artifact()
-        ignoreGradleMetadataRedirection()
-      }
-    }
+    mavenCentral()
   }
 
   apply plugin: 'java'

jib-cli/src/integration-test/resources/jarTest/spring-boot/settings-layered.gradle

@@ -1,2 +1,8 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
 rootProject.name = 'spring-boot'
 rootProject.buildFileName = 'build-layered.gradle'

jib-cli/src/integration-test/resources/jarTest/spring-boot/settings.gradle

@@ -1 +1,7 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
 rootProject.name = 'spring-boot'

jib-gradle-plugin/src/integration-test/resources/gradle/projects/spring-boot/settings.gradle

@@ -1 +1,7 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        gradlePluginPortal()
+    }
+}
 rootProject.name = 'spring-boot'

settings.gradle

@@ -1,3 +1,18 @@
+pluginManagement {
+    repositories {
+        mavenCentral()
+        // Workaround from: https://github.com/gradle/gradle/issues/15406#issuecomment-1020352934
+        gradlePluginPortal {
+            this as MavenArtifactRepository
+            metadataSources {
+                mavenPom()
+                artifact()
+                ignoreGradleMetadataRedirection()
+            }
+        }
+    }
+}
+
 include ":jib-build-plan"
 include ":jib-plugins-extension-common"
 include ":jib-gradle-plugin-extension-api"