fix test

Author: ashithasantosh

authz/src/main/java/io/grpc/authz/FileWatcherAuthorizationServerInterceptor.java

@@ -17,6 +17,7 @@
 package io.grpc.authz;
 
 import static com.google.common.base.Preconditions.checkNotNull;
+import static java.nio.charset.StandardCharsets.UTF_8;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Strings;
@@ -77,7 +78,7 @@ void updateInternalInterceptor() throws IOException {
     if (currentTime.equals(lastModifiedTime)) {
       return;
     }
-    String policyContents = new String(Files.readAllBytes(policyFile.toPath()));
+    String policyContents = new String(Files.readAllBytes(policyFile.toPath()), UTF_8);
     lastModifiedTime = currentTime;
     internalAuthzServerInterceptor = AuthorizationServerInterceptor.create(policyContents);
     if (testCallback != null) {