code: /*
   * 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.skywalking.oap.server.telemetry.api;
  
  /**
   * Tag for the target metrics.
   * <p>
   * The tag values should be set in putting value phase.
   */
  public class MetricsTag {
      public static final Keys EMPTY_KEY = new Keys();
      public static final Values EMPTY_VALUE = new Values();
  
      public static class Keys {
          private String[] keys;
  
          public Keys() {
              this.keys = new String[0];
          }
  
          public Keys(String... keys) {
              this.keys = keys;
          }
  
          public String[] getKeys() {
              return keys;
          }
      }
  
      public static class Values {
          private String[] values;
  
          public Values(Keys keys) {
              this.values = new String[0];
          }
  
          public Values(String... keys) {
              this.values = keys;
          }
  
          public String[] getValues() {
              return values;
          }
      }
  }
  