Checkstyle fixes

sdk/src/main/java/io/opentelemetry/sdk/common/export/CompletableResultCode.java

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2019, OpenTelemetry Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package io.opentelemetry.sdk.common.export;
 
 import java.util.ArrayList;
@@ -12,12 +28,12 @@
  * select JDK 8 or greater as a baseline, and also to offer familiarity to developers.
  */
 public class CompletableResultCode {
-  /** A convenience for declaring success */
+  /** A convenience for declaring success. */
   public static CompletableResultCode ofSuccess() {
     return SUCCESS;
   }
 
-  /** A convenience for declaring failure */
+  /** A convenience for declaring failure. */
   public static CompletableResultCode ofFailure() {
     return FAILURE;
   }