presto-main/src/main/java/io/prestosql/sql/planner/TranslationMap.java/TranslationMap/setFieldMappings
class TranslationMap:    public void setFieldMappings(List<Symbol> symbols)
    {
        checkArgument(symbols.size() == fieldSymbols.length, "size of symbols list (%s) doesn't match number of expected fields (%s)", symbols.size(), fieldSymbols.length);

        for (int i = 0; i < symbols.size(); i++) {
            this.fieldSymbols[i] = symbols.get(i);
        }
    }