public File getPostgreSQLSSLClientKeyFile() throws GuacamoleException {
        return getProperty(PostgreSQLGuacamoleProperties.POSTGRESQL_SSL_KEY_FILE);
    }
Return the SSL client private key file to use to make the connection to the
PostgreSQL server.

@return
    The SSL client private key file to use for the PostgreSQL connection.
@throws GuacamoleException
    If an error occurs retrieving the value from guacamole.properties.
extensions/guacamole-auth-jdbc/modules/guacamole-auth-jdbc-postgresql/src/main/java/org/apache/guacamole/auth/postgresql/conf/PostgreSQLEnvironment.java