The hibernate wizard "Hibernate Mapping Files And POJOs from database" has a NullPointerException when connecting to a Firebird database:

226109 [AWT-EventQueue-0] INFO org.hibernate.connection.ConnectionProviderFactory - Initializing connection provider: org.netbeans.modules.hibernate.util.CustomJDBCConnectionProvider
INFO [org.netbeans.modules.hibernate.util.CustomJDBCConnectionProvider]: Loaded JDBC driver 
INFO [org.netbeans.modules.hibernate.util.CustomJDBCConnectionProvider]: Got connection.. returning
INFO [org.netbeans.modules.hibernate.wizards.HibernateCodeGenWizardDescriptor]: access to hibernate fails.
java.lang.NullPointerException
	at org.hibernate.cfg.SettingsFactory.buildSettings(SettingsFactory.java:115)
	at org.hibernate.cfg.Configuration.buildSettingsInternal(Configuration.java:2863)
	at org.hibernate.cfg.Configuration.buildSettings(Configuration.java:2855)
	at org.hibernate.cfg.JDBCMetaDataConfiguration.readFromJDBC(JDBCMetaDataConfiguration.java:41)
	at org.netbeans.modules.hibernate.wizards.HibernateCodeGenWizardDescriptor.checkConfig(HibernateCodeGenWizardDescriptor.java:289)
[catch] at org.netbeans.modules.hibernate.wizards.HibernateCodeGenWizardDescriptor.isValid(HibernateCodeGenWizardDescriptor.java:179)
	at org.openide.WizardDescriptor.updateStateOpen(WizardDescriptor.java:874)
	at org.openide.WizardDescriptor.updateState(WizardDescriptor.java:822)
	at org.openide.loaders.TemplateWizard.updateState(TemplateWizard.java:754)
	at org.netbeans.modules.project.ui.NewFileWizard.updateState(NewFileWizard.java:135)
	at org.openide.WizardDescriptor._updateState(WizardDescriptor.java:800)

After digging into the code of Netbeans and adding extra logging to Jaybird, I found that the problem is that Netbeans loads the driver with a custom classloader that doesn't return resources in /META-INF/services. 

Jaybird (the Firebird JDBC driver) uses plugins for its protocol implementation (eg the Type 4 implementation, Type 2 native, Type 2 embedded). These are listed in a file in /META-INF/services/ (specifically /META-INF/services/org.firebirdsql.gds.impl.GDSFactoryPlugin), and are loaded with a mechanism similar to java.util.ServiceLoader. This also allows third-parties to add protocol implementations. For example as a workaround, or for special needs; I know a company used this mechanism to provide a driver that could translate Oracle syntax to Firebird.

The change were a Netbeans classloader ignores the existence of all files in /META-INF/services was added in:
http://hg.netbeans.org/main-silver?cmd=changeset;node=c8413dd446c2
in response to bug:
https://netbeans.org/bugzilla/show_bug.cgi?id=194915

I have added a workaround in Jaybird, but I think it is a bug in Netbeans that it purposefully refuses to load files that may be required by a Java library.

See also:
http://tracker.firebirdsql.org/browse/JDBC-325
http://stackoverflow.com/a/18920383/466862
http://stackoverflow.com/questions/18921352/using-meta-inf-services-for-internal-plumbing-of-driver

Reproducing this requires Jaybird 2.2.3 or earlier, as I added a workaround to the upcoming Jaybird 2.2.4.

When investigating this, I noticed that when going through the wizard, *two* database connections are made: 
one by org.netbeans.modules.hibernate.util.HibernateUtil that succeeds but isn't used, 
and another by org.netbeans.modules.hibernate.util.CustomJDBCConnectionProvider which fails because of the classloading issue described in my previous comment.

This bug is related to 202333 and 212636