presto-main/src/main/java/io/prestosql/sql/planner/RelationPlanner.java/RelationPlanner/initializePlanBuilder
class RelationPlanner:    private PlanBuilder initializePlanBuilder(RelationPlan relationPlan)
    {
        TranslationMap translations = new TranslationMap(relationPlan, analysis, lambdaDeclarationToSymbolMap);

        // Make field->symbol mapping from underlying relation plan available for translations
        // This makes it possible to rewrite FieldOrExpressions that reference fields from the underlying tuple directly
        translations.setFieldMappings(relationPlan.getFieldMappings());

        return new PlanBuilder(translations, relationPlan.getRoot());
    }