presto-main/src/main/java/io/prestosql/util/JsonUtil.java/RowBlockBuilderAppender/RowBlockBuilderAppender
class RowBlockBuilderAppender:        RowBlockBuilderAppender(BlockBuilderAppender[] fieldAppenders, Optional<Map<String, Integer>> fieldNameToIndex)
        {
            this.fieldAppenders = fieldAppenders;
            this.fieldNameToIndex = fieldNameToIndex;
        }