Enable SQL log for tables in flowable engine

Hi, we have integrated flowable 6.4.2 into our web application, which allow user to submit an application form and used flowable to handle the approval process.
Our web application used hibernate for OR mapping and log4j for console log.
We would like to enable SQL log for flowable database tables (ACT_*) but failed.
Our project’s dependency:

		<dependency>
			<groupId>org.hibernate</groupId>
			<artifactId>hibernate-core</artifactId>
			<version>4.2.21.Final</version>
		</dependency>
		<dependency>
			<groupId>log4j</groupId>
			<artifactId>log4j</artifactId>
			<version>1.2.17</version>
		</dependency>

		<dependency>
			<groupId>org.flowable</groupId>
			<artifactId>flowable-engine</artifactId>
			<version>6.4.2</version>
		</dependency>
		<dependency>
		    <groupId>org.flowable</groupId>
		    <artifactId>flowable-job-service</artifactId>
		    <version>6.4.2</version>
		</dependency>
		<!-- https://mvnrepository.com/artifact/org.flowable/flowable-spring -->
		<dependency>
		    <groupId>org.flowable</groupId>
		    <artifactId>flowable-spring</artifactId>
			<version>6.4.2</version>
		</dependency>

our log4j properties file:

log4j.rootLogger=DEBUG,console

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=[%c]-[%p] %m%n

log4j.logger.org.flowable=DEBUG
log4j.logger.org.hibernate=info

Under this configuration, the application server is not able to catch any SQL logs from flowable.

In the same workspace, i created a standalone java project with the same log4j and flowable config and i was able to grab the SQL logs .

Any additional configuration that was missing in the web application?