Merge branch 'stable-2.16' into stable-3.0

* stable-2.16:
  OperatingSystemMXBeanFactory: Add a default constructor
  Remove unnecessary @SuppressWarnings("restriction")
  Add mirror for downloading Bazel rules.
  Add test that verifies 'visibleto' predicate for group

Change-Id: I48f7a0d3121edc9dda7726c445aa044bb23290a2

WORKSPACE

@@ -29,7 +29,10 @@ http_archive(
     name = "io_bazel_rules_closure",
     sha256 = "b9c2bc6ba377aa497eb7c31681d34404febf9d4e3c9c7d98ce0d78238a0af20f",
     strip_prefix = "rules_closure-0.31",
-    urls = ["https://github.com/davido/rules_closure/archive/V0.31.tar.gz"],
+    urls = [
+        "https://github.com/davido/rules_closure/archive/V0.31.tar.gz",
+        "https://gerrit-ci.gerritforge.com/lib/V0.31.tar.gz",
+    ],
 )
 
 # File is specific to Polymer and copied from the Closure Github -- should be

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanFactory.java

@@ -20,10 +20,11 @@ import java.lang.management.ManagementFactory;
 import java.lang.management.OperatingSystemMXBean;
 import java.util.Arrays;
 
-@SuppressWarnings("restriction")
 class OperatingSystemMXBeanFactory {
   private static final FluentLogger logger = FluentLogger.forEnclosingClass();
 
+  private OperatingSystemMXBeanFactory() {}
+
   static OperatingSystemMXBeanInterface create() {
     OperatingSystemMXBean sys = ManagementFactory.getOperatingSystemMXBean();
     if (sys instanceof UnixOperatingSystemMXBean) {

java/com/google/gerrit/metrics/proc/OperatingSystemMXBeanUnixNative.java

@@ -16,7 +16,6 @@ package com.google.gerrit.metrics.proc;
 
 import com.sun.management.UnixOperatingSystemMXBean;
 
-@SuppressWarnings("restriction")
 class OperatingSystemMXBeanUnixNative implements OperatingSystemMXBeanInterface {
   private final UnixOperatingSystemMXBean sys;