P4
G1RSetScanBlockSize is obsolete in JDK 15, so it needs to be moved to the list of obsolete flags.
Further the flag itself can be removed as it is covered by the table; there is not functionality or tests to remove as it has not been used for some time.
Further the flag itself can be removed as it is covered by the table; there is not functionality or tests to remove as it has not been used for some time.