content: /*
   * Licensed to the Apache Software Foundation (ASF) under one
   * or more contributor license agreements.  See the NOTICE file
   * distributed with this work for additional information
   * regarding copyright ownership.  The ASF licenses this file
   * to you 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 org.apache.beam.sdk.metrics;
  
  /**
   * A metric that reports set of unique string values. This metric is backed by {@link
   * java.util.HashSet} and hence it does not maintain any ordering.
   */
  public interface StringSet extends Metric {
  
    /** Add a value to this set. */
    void add(String value);
  
    /** Add values to this set. */
    default void add(String... values) {
      for (String value : values) {
        add(value);
      }
    }
  }
  