Connection RuntimeCast Error

I wrapped some gt modules (gt-geojson, gt-jdbc, gt-jdbc-oracle, etc.) to OSGi bundle in my application.
There is the following exception, when calling FeatureJSON.writeFeatureCollection().

Should it be add the clause "((DelegatingConnection)conn).getInnermostDelegate();" somewhere?

2011.06.21 17:23:28.127 WARN [1386211@qtp-1562305-0] [demo-app] Failed to writeFeatureCollection (java.lang.RuntimeException: java.sql.SQLException: Could not obtain native oracle connection for class org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper) java.lang.RuntimeException: java.sql.SQLException: Could not obtain native oracle connection for class org.apache.commons.dbcp.PoolingDataSource$PoolGuardConnectionWrapper
at org.geotools.jdbc.JDBCFeatureReader.next(JDBCFeatureReader.java:652)
at org.geotools.jdbc.JDBCFeatureReader.next(JDBCFeatureReader.java:84)
at org.geotools.data.store.ContentFeatureCollection$WrappingFeatureIterator.next(ContentFeatureCollection.java:189)
at org.geotools.data.store.ContentFeatureCollection$WrappingFeatureIterator.next(ContentFeatureCollection.java:169)
at org.geotools.geojson.feature.FeatureJSON$FeatureCollectionEncoder.writeJSONString(FeatureJSON.java:473)
at org.json.simple.JSONValue.writeJSONString(Unknown Source)
at org.json.simple.JSONObject.writeJSONString(Unknown Source)
at org.geotools.geojson.GeoJSONUtil.encode(GeoJSONUtil.java:244)
at org.geotools.geojson.feature.FeatureJSON.writeFeatureCollection(FeatureJSON.java:248)