logback.xml :

<appender name="DB" class="ch.qos.logback.classic.db.DBAppender">
<connectionSource class="ch.qos.logback.core.db.DataSourceConnectionSource">
<dataSource class ="com.mchange.v2.c3p0.ComboPooledDataSource"></dataSource>
<driverClass>com.mysql.jdbc.Driver</driverClass>
<url>jdbc:mysql://localhost:3306/mrb</url>
<user>root</user>
<password>admin</password>
</connectionSource>
</appender>

Java code (using DBAppender):

Date dateFrom = null;
log.info("Processing code {}; code type is {}; request date {}; record from date {}",new Object[]

{ code, codeType, new Date(), dateFrom }

);

DBAppender had null pointer exception on 141 line because of dateFrom, but this exception is swallowed and not shown.