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.coders;
  
  import java.util.Collection;
  import java.util.List;
  import org.apache.beam.sdk.values.TypeDescriptor;
  import org.apache.beam.sdk.values.TypeParameter;
  
  /**
   * A {@link CollectionCoder} encodes {@link Collection Collections} in the format of {@link
   * IterableLikeCoder}.
   */
  public class CollectionCoder<T> extends IterableLikeCoder<T, Collection<T>> {
  
    public static <T> CollectionCoder<T> of(Coder<T> elemCoder) {
      return new CollectionCoder<>(elemCoder);
    }
  
    /////////////////////////////////////////////////////////////////////////////
    // Internal operations below here.
  
    /**
     * {@inheritDoc}
     *
     * @return the decoded elements directly, since {@link List} is a subtype of {@link Collection}.
     */
    @Override
    protected final Collection<T> decodeToIterable(List<T> decodedElements) {
      return decodedElements;
    }
  
    protected CollectionCoder(Coder<T> elemCoder) {
      super(elemCoder, "Collection");
    }
  
    @Override
    public TypeDescriptor<Collection<T>> getEncodedTypeDescriptor() {
      return new TypeDescriptor<Collection<T>>() {}.where(
          new TypeParameter<T>() {}, getElemCoder().getEncodedTypeDescriptor());
    }
  }
  