java.lang.NullPointerException
at ch.qos.logback.classic.Logger.callTurboFilters(Logger.java:769) [logback-classic-0.9.15.jar:na]
at ch.qos.logback.classic.Logger.isTraceEnabled(Logger.java:641) [logback-classic-0.9.15.jar:na]
at ch.qos.logback.classic.Logger.isTraceEnabled(Logger.java:637) [logback-classic-0.9.15.jar:na]
at org.hibernate.event.def.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:198) [hibernate-core-3.3.0.SP1.jar:3.3.0.SP1]
at org.hibernate.event.def.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:126) [hibernate-core-3.3.0.SP1.jar:3.3.0.SP1]
at org.hibernate.impl.SessionImpl.fireLoad(SessionImpl.java:905) [hibernate-core-3.3.0.SP1.jar:3.3.0.SP1]

Hibernate calls if ( log.isTraceEnabled() ).