JPA: NPEs when try to create some error markers

Earlier we used null as turget object in some places. Probably API changed in the place and null should not be used any more.

Error log example:

Nested exception 1: java.lang.NullPointerException
at org.eclipse.jpt.jpa.core.internal.validation.JpaValidationPreferences.getProject(JpaValidationPreferences.java:63)
at org.eclipse.jpt.jpa.core.internal.validation.JpaValidationPreferences.getProblemSeverityPreference(JpaValidationPreferences.java:46)
at org.jboss.tools.hibernate.jpt.core.internal.validation.HibernateJpaValidationMessage.buildMessage(HibernateJpaValidationMessage.java:50)
at org.jboss.tools.hibernate.jpt.core.internal.validation.HibernateJpaValidationMessage.buildMessage(HibernateJpaValidationMessage.java:37)
at org.jboss.tools.hibernate.jpt.core.internal.validation.HibernateJpaValidationMessage.buildMessage(HibernateJpaValidationMessage.java:32)
at org.jboss.tools.hibernate.jpt.core.internal.context.orm.HibernateOrmTableImpl.buildDefaultDBTableName(HibernateOrmTableImpl.java:80)