WrapperDataSource instead of OracleDatasource in JBoss AS7

I have defined oracle datasource in JBoss standalone.xml as mentioned below:

<datasource jndi-name="java:jboss/datasources/DefaultDS" pool-name="DefaultDS_pool" enabled="true" use-java-context="true">
                    <connection-url>jdbc:oracle:thin:@localhost:1521:C3S</connection-url>
                    <driver>oracle</driver>
                    <security>
                        <user-name>jboss</user-name>
                        <password>sysadm</password>
                    </security>
                </datasource>
                <drivers>
                    <driver name="oracle" module="com.oracle.jdbc">
                        <xa-datasource-class>oracle.jdbc.xa.client.OracleXADataSource</xa-datasource-class>
                        <datasource-class>oracle.jdbc.OracleDriver</datasource-class>
                    </driver>

and i am using this datasource in bean class using below code:

@Resource(mappedName="java:jboss/datasources/DefaultDS")
DataSource driver;

But i am not able to get oracle datasource instead only getting wrapperdatasource object. I was under impression as i have defined oracle datasource so i will get the same.

So please let me know how can i get oracle datasource instead of wrapperdatasource in jboss as7?