there are issues with manual JCK tests if Nimbus LaF specified:

api/javax_swing/interactive/JTableTests.html#JTable[JTableTest0004]
api/javax_swing/interactive/JTableTests.html#JTable[JTableTest0005]
api/javax_swing/interactive/JTableTests.html#JTable[JTableTest0006]
api/javax_swing/interactive/JTableTests.html#JTable[JTableTest0007]

show grid checkbox is not selected at the beginning of the test;
grid is shown not for all columns (see screenshot attached)

source of the test:
http://stt-13.russia/set/stt/jck_promotions/6b/b24/binaries/JCK-runtime-6b/tests/api/javax_swing/interactive/JTableTests.html
also api/javax_swing/interactive/JTableTests.html#JTable[JTableTest0013] affected - change of color doesn't affect appearance of the table.
The issue mentioned in the related CR 6936495 is still reproducible. So the checkbox in the JCK test mentioned in 6937798 is coming up unchecked for Nimbus L&F

The fix was partial in the 6u21-b04 PIT. So changing the status to Fix Failed and removing the verify-PIT keyword.