Mapping Diagram doesn't work if hibernate.dialect not defined

java.lang.NullPointerException
at java.lang.Class.forName0(Native Method)
at java.lang.Class.forName(Class.java:164)
at org.jboss.tools.hibernate.ui.view.views.OrmModelNameVisitor.getColumnSqlType(OrmModelNameVisitor.java:98)
at org.jboss.tools.hibernate.ui.view.views.OrmModelNameVisitor.visitDatabaseColumn(OrmModelNameVisitor.java:54)
at org.jboss.tools.hibernate.ui.view.views.OrmLabelProvider.getText(OrmLabelProvider.java:127)
at org.jboss.tools.hibernate.ui.veditor.editors.parts.ShapeEditPart.createFigure(ShapeEditPart.java:79)
at org.eclipse.gef.editparts.AbstractGraphicalEditPart.getFigure(AbstractGraphicalEditPart.java:445)
at org.eclipse.gef.editparts.AbstractGraphicalEditPart.addChildVisual(AbstractGraphicalEditPart.java:197)
at org.eclipse.gef.editparts.AbstractEditPart.addChild(AbstractEditPart.java:197)
at org.eclipse.gef.editparts.AbstractEditPart.refreshChildren(AbstractEditPart.java:727)
at org.eclipse.gef.editparts.AbstractEditPart.refresh(AbstractEditPart.java:677)
at org.eclipse.gef.editparts.AbstractGraphicalEditPart.refresh(AbstractGraphicalEditPart.java:564)...