hibernate.connection.provider_class with Hibernate 4

[momatej]

Does anyone know the value for hibernate.connection.provider_class with hibernate 4?

I tried org.hibernate.service.jdbc.connections.internal.C3 P0ConnectionProvider but had no luck. It gives me :

2011-12-13/14:45:22.364/EST [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#0] WARN  com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@315252d2 -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.lang.NullPointerException
	at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(Unknown Source)
	at java.sql.DriverManager.getDriver(Unknown Source)
	at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
	at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
2011-12-13/14:45:22.364/EST [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#2] WARN  com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@79db5f5e -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.lang.NullPointerException
	at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(Unknown Source)
	at java.sql.DriverManager.getDriver(Unknown Source)
	at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
	at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
2011-12-13/14:45:22.364/EST [com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread-#1] WARN  com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask@13bb724a -- Acquisition Attempt Failed!!! Clearing pending acquires. While trying to acquire a needed new resource, we failed to succeed more than the maximum number of allowed acquisition attempts (30). Last acquisition attempt exception: 
java.lang.NullPointerException
	at sun.jdbc.odbc.JdbcOdbcDriver.getProtocol(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.knownURL(Unknown Source)
	at sun.jdbc.odbc.JdbcOdbcDriver.acceptsURL(Unknown Source)
	at java.sql.DriverManager.getDriver(Unknown Source)
	at com.mchange.v2.c3p0.DriverManagerDataSource.driver(DriverManagerDataSource.java:223)
	at com.mchange.v2.c3p0.DriverManagerDataSource.getConnection(DriverManagerDataSource.java:119)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:143)
	at com.mchange.v2.c3p0.WrapperConnectionPoolDataSource.getPooledConnection(WrapperConnectionPoolDataSource.java:132)
	at com.mchange.v2.c3p0.impl.C3P0PooledConnectionPool$1PooledConnectionResourcePoolManager.acquireResource(C3P0PooledConnectionPool.java:137)
	at com.mchange.v2.resourcepool.BasicResourcePool.doAcquire(BasicResourcePool.java:1014)
	at com.mchange.v2.resourcepool.BasicResourcePool.access$800(BasicResourcePool.java:32)
	at com.mchange.v2.resourcepool.BasicResourcePool$AcquireTask.run(BasicResourcePool.java:1810)
	at com.mchange.v2.async.ThreadPoolAsynchronousRunner$PoolThread.run(ThreadPoolAsynchronousRunner.java:547)
2011-12-13/14:45:22.371/EST [Thread-17] WARN  HHH000342: Could not obtain connection to query metadata : Connections could not be acquired from the underlying database!