Keycloak db query in source codes [closed]

I want to make some changes in the ValidateUsername and AbstractUsernameFormAuthenticator java classes of Keycloak source codes and access the tables of the H2 database of Keycloak.

Suppose I have created a new table in H2 Keycloak's DB (called MyTable) and it consists of 2 column (Username and specific attribute). Now I want to access MyTable in those classes mentioned.

Note 1: I don't want to develop a new SPI to be used instead of these 2 providers. I just want to make some changes on them.

Note 2: I can also use DriverManager.getConnection() and execute my commands using executeQuery but I am searching for a better performance way to access the table. (Since Keycloak is connected to the DB already to perform some functions like user.getId ...)