presto-example-http/src/main/java/io/prestosql/plugin/example/ExampleRecordCursor.java/ExampleRecordCursor/getType
class ExampleRecordCursor:    @Override
    public Type getType(int field)
    {
        checkArgument(field < columnHandles.size(), "Invalid field index");
        return columnHandles.get(field).getColumnType();
    }