FULL PRODUCT VERSION :
java version " 1.7.0_17 "
Java(TM) SE Runtime Environment (build 1.7.0_17-b02)
Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)

ADDITIONAL OS VERSION INFORMATION :
Microsoft Windows [Version 6.1.7601]

A DESCRIPTION OF THE PROBLEM :
  Bug discussion:
https://forums.oracle.com/forums/thread.jspa?threadID=2543593&tstart=0

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
Use any java.sql.Clob implementation other than the Oracle provided one. One such implementation is posted in the given thread, follow the link.
Pass it to PreparedStatement.setClob()
Do PreparedStatement.execute()

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
No errors on .execute()
ACTUAL -
Complains about a data field in Datum being null (which there is a workaround for) but after workaround still complains that ClobLocator is null or something like that.

REPRODUCIBILITY :
This bug can be reproduced always.

CUSTOMER SUBMITTED WORKAROUND :
extending oracle.types.CLOB and calling setBytes() gets rid of the data=null error, but no use with the Clob locator thing.