Check content of non-null URLs in testGetEntryUrlOrNull

The test doesn't check the content of all the non-null URLs
returned by the ClassPathURLStreamHandler.getEntryUrlOrNull(),
it mainly asserts their non-null status. This change adds checks
for the content as well to highlight the difference in behaviour
caused by changes for OpenJDK

Change-Id: I898cbf751105e2cbe5f197be73bd07a47376dae6
1 file changed