如何获取Apache Beam SQL查询的输出模式？

import org.apache.beam.sdk.Pipeline;
import org.apache.beam.sdk.extensions.sql.SqlTransform;
import org.apache.beam.sdk.schemas.Schema;
import org.apache.beam.sdk.values.PCollection;

public class BeamSqlExample {
    public static void main(String[] args) {
        // 创建一个数据处理流水线
        Pipeline pipeline = Pipeline.create();

        // 从外部数据源读取数据，创建一个PCollection对象
        PCollection<MyDataClass> input = pipeline.apply(/* 读取数据的Transform */);

        // 执行SQL查询
        PCollection<Row> output = input.apply(SqlTransform.query("SELECT * FROM input"));

        // 获取查询的输出模式
        Schema outputSchema = SqlTransform.getOutputSchema("SELECT * FROM input");

        // 打印输出模式的字段信息
        for (Schema.Field field : outputSchema.getFields()) {
            System.out.println("Field name: " + field.getName());
            System.out.println("Field type: " + field.getType());
        }

        // 运行流水线
        pipeline.run();
    }
}