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
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  package org.apache.beam.examples.multilanguage.schematransforms;
  
  import static org.apache.beam.examples.multilanguage.schematransforms.JavaCountProvider.Configuration;
  
  import com.google.auto.service.AutoService;
  import com.google.auto.value.AutoValue;
  import org.apache.beam.sdk.schemas.AutoValueSchema;
  import org.apache.beam.sdk.schemas.Schema;
  import org.apache.beam.sdk.schemas.annotations.DefaultSchema;
  import org.apache.beam.sdk.schemas.transforms.SchemaTransform;
  import org.apache.beam.sdk.schemas.transforms.SchemaTransformProvider;
  import org.apache.beam.sdk.schemas.transforms.TypedSchemaTransformProvider;
  import org.apache.beam.sdk.transforms.Count;
  import org.apache.beam.sdk.transforms.MapElements;
  import org.apache.beam.sdk.util.Preconditions;
  import org.apache.beam.sdk.values.PCollection;
  import org.apache.beam.sdk.values.PCollectionRowTuple;
  import org.apache.beam.sdk.values.Row;
  import org.apache.beam.sdk.values.TypeDescriptors;
  
  @AutoService(SchemaTransformProvider.class)
  public class JavaCountProvider extends TypedSchemaTransformProvider<Configuration> {
    @Override
    public String identifier() {
      return "beam:schematransform:org.apache.beam:count:v1";
    }
  
    @Override
    protected SchemaTransform from(Configuration configuration) {
      return new JavaCountTransform();
    }
  
    static class JavaCountTransform extends SchemaTransform {
      static final Schema OUTPUT_SCHEMA =
          Schema.builder().addStringField("word").addInt64Field("count").build();
  
      @Override
      public PCollectionRowTuple expand(PCollectionRowTuple input) {
        PCollection<Row> wordCounts =
            input
                .get("input")
                .apply(Count.perElement())
                .apply(
                    MapElements.into(TypeDescriptors.rows())
                        .via(
                            kv ->
                                Row.withSchema(OUTPUT_SCHEMA)
                                    .withFieldValue(
                                        "word",
                                        Preconditions.checkStateNotNull(
                                            kv.getKey().getString("word")))
                                    .withFieldValue("count", kv.getValue())
                                    .build()))
                .setRowSchema(OUTPUT_SCHEMA);
  
        return PCollectionRowTuple.of("output", wordCounts);
      }
    }
  
    @DefaultSchema(AutoValueSchema.class)
    @AutoValue
    public abstract static class Configuration {}
  }
  