HttpURLConnection.filterHeaderField method returns null where empty string is expected

SHORT SUMMARY: NPE seen in HttpSOAPConnection.post method
INDICATORS:
NPE occurring in
com.sun.xml.internal.messaging.saaj.client.p2p.HttpSOAPConnection.post
when run through a plugin/webstart environment.
COUNTER INDICATORS:
TRIGGERS:
Presense of only HttpOnly headers in the Set-Cookie headers value which
results in a
null value being passed to calling code in plugin environment.
KNOWN WORKAROUND:
N/A
PRESENT SINCE:
7u4 (https://jbs.oracle.com/bugs/browse/JDK-7095980)
HOW TO VERIFY:
Will write a regression testcase.
NOTES FOR SE:
REGRESSION: Y