Aggregation pushdown in JDBC connector

[ArthurBesse]

I am trying to create a custom JDBC connector, and will appreciate any help for solving the following problem.

I have the following query:

SELECT COUNT(*) AS ROWS_COUNT, AVG(PRICE) AS AVERAGE_PRICE, SIZE FROM CATALOG_NAME.SCHEMA_NAME.TABLE_NAME GROUP BY SIZE;

But when I execute this query my jdbc driver receives the following modified query

SELECT PRICE, SIZE FROM CATALOG_NAME.SCHEMA_NAME.TABLE_NAME

As you can see my driver don't get "group by" part of query as well as aggregation functions in projection part, and this is not what I want. I need to pushdown these parts to my driver.
I couldn't find any information on how plugins should indicate that they support pushdown in developer guide, so if there is such information in documentation please let me know.

Code for my JDBC connector is almost the same as the jdbc-connector-example code in repository with minimal changes.

P.s. I'm new to trino, so I appreciate your patience and willingness to help.