Rule.toString() sometimes throws org.hibernate.LazyInitializationException

org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: org.sonar.api.rules.Rule.params, no session or session was closed
        at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationException(AbstractPersistentCollection.java:380) [hibernate-core-3.3.2.GA.jar:3.3.2.GA]
        at org.hibernate.collection.AbstractPersistentCollection.throwLazyInitializationExceptionIfNotConnected(AbstractPersistentCollection.java:372) [hibernate-core-3.3.2.GA.jar:3.3.2.GA]
        at org.hibernate.collection.AbstractPersistentCollection.initialize(AbstractPersistentCollection.java:365) [hibernate-core-3.3.2.GA.jar:3.3.2.GA]
        at org.hibernate.collection.AbstractPersistentCollection.read(AbstractPersistentCollection.java:108) [hibernate-core-3.3.2.GA.jar:3.3.2.GA]
        at org.hibernate.collection.PersistentBag.toString(PersistentBag.java:506) [hibernate-core-3.3.2.GA.jar:3.3.2.GA]
        at java.lang.String.valueOf(String.java:2826) [na:1.6.0_29]
        at java.lang.StringBuffer.append(StringBuffer.java:219) [na:1.6.0_29]
        at org.apache.commons.lang.builder.ToStringStyle.appendDetail(ToStringStyle.java:597) [commons-lang-2.6.jar:2.6]
        at org.apache.commons.lang.builder.ToStringStyle.appendInternal(ToStringStyle.java:472) [commons-lang-2.6.jar:2.6]
        at org.apache.commons.lang.builder.ToStringStyle.append(ToStringStyle.java:435) [commons-lang-2.6.jar:2.6]
        at org.apache.commons.lang.builder.ToStringBuilder.append(ToStringBuilder.java:851) [commons-lang-2.6.jar:2.6]
        at org.apache.commons.lang.builder.ReflectionToStringBuilder.appendFieldsIn(ReflectionToStringBuilder.java:606) [commons-lang-2.6.jar:2.6]
        at org.apache.commons.lang.builder.ReflectionToStringBuilder.toString(ReflectionToStringBuilder.java:765) [commons-lang-2.6.jar:2.6]
        at org.sonar.api.rules.Rule.toString(Rule.java:399) [sonar-plugin-api-2.13-SNAPSHOT.jar:na]