Use root locale for String.format

Author: felixbarny

server/src/test/java/org/elasticsearch/common/network/InetAddressesTests.java

@@ -27,6 +27,7 @@
 import java.net.UnknownHostException;
 import java.nio.charset.StandardCharsets;
 import java.util.Enumeration;
+import java.util.Locale;
 
 import static org.hamcrest.Matchers.equalTo;
 
@@ -265,7 +266,7 @@ public void testAppendHexBytes() {
             byte b1 = randomByte();
             byte b2 = randomByte();
             // The expected string is the hex representation of the two bytes, padded to 4 characters
-            String expected = String.format("%1$04x", (b1 & 0xFF) << 8 | b2 & 0xFF);
+            String expected = String.format(Locale.ROOT, "%1$04x", (b1 & 0xFF) << 8 | b2 & 0xFF);
             byte[] hex = new byte[4];
             InetAddresses.appendHexBytes(hex, 0, b1, b2);
             String actual = new String(hex, StandardCharsets.US_ASCII);