fix thread check for unit test

Author: Vladimir Dolzhenko

plugins/repository-s3/src/main/java/org/elasticsearch/repositories/s3/S3RepositoryPlugin.java

@@ -61,7 +61,7 @@ public class S3RepositoryPlugin extends Plugin implements RepositoryPlugin, Relo
         });
     }
 
-    private final S3Service service;
+    protected final S3Service service;
 
     public S3RepositoryPlugin(final Settings settings) {
         this(settings, new S3Service(settings));

plugins/repository-s3/src/test/java/org/elasticsearch/repositories/s3/RepositoryCredentialsTests.java

@@ -80,6 +80,16 @@ AmazonS3 buildClient(AWSCredentialsProvider credentials, ClientConfiguration con
         ProxyS3RepositoryPlugin(Settings settings) {
             super(settings, new ProxyS3Service(settings));
         }
+
+        @Override
+        protected S3Repository createRepository(RepositoryMetaData metadata, Settings settings, NamedXContentRegistry registry) {
+            return new S3Repository(metadata, settings, registry, service){
+                @Override
+                protected void verificationThreadCheck() {
+
+                }
+            };
+        }
     }
 
     public void testRepositoryCredentialsOverrideSecureCredentials() throws IOException {