In line 84 and also line 304 of WindowsFileCopy.java in java.base/windows/classes/sun/nio/fs/ the details message lacks the string representation of the actual option instance that is not supported.

Proposal: replace
    throw new UnsupportedOperationException("Unsupported copy option");
with
    throw new UnsupportedOperationException("Unsupported copy option: " + option);