Here I get 
	java.lang.ClassCastException: org.hibernate.metamodel.relational.Column cannot be cast to org.hibernate.mapping.Column
		at org.hibernate.dialect.unique.DefaultUniqueDelegate.uniqueConstraintSql(DefaultUniqueDelegate.java:138)
		at org.hibernate.dialect.unique.DefaultUniqueDelegate.getAlterTableToAddUniqueKeyCommand(DefaultUniqueDelegate.java:131)
		at org.hibernate.metamodel.relational.UniqueKey.sqlCreateStrings(UniqueKey.java:52)
		at org.hibernate.metamodel.relational.Database.addSqlCreateStrings(Database.java:203)
		at org.hibernate.metamodel.relational.Database.generateSchemaCreationScript(Database.java:119)
		at org.hibernate.tool.hbm2ddl.SchemaExport.<init>(SchemaExport.java:146)
		at org.hibernate.internal.SessionFactoryImpl.<init>(SessionFactoryImpl.java:927)
		at org.hibernate.metamodel.source.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:66)
		at org.hibernate.metamodel.source.internal.MetadataImpl.buildSessionFactory(MetadataImpl.java:459)
		at org.hibernate.shards.ShardedConfiguration.buildFactory(ShardedConfiguration.java:178)
I didn't find how to avoid this exception. @brmeyer do you know how to avoid it or it is bug in hibernate core?