In boot-jdk.m4 in BOOTJDK_CHECK_WELL_KNOWN_LOCATIONS, we should really be doing like this:

BOOTJDK_FIND_BEST_JDK_IN_WINDOWS_VIRTUAL_DIRECTORY([{'ProgramFiles(x86)'}])

However, the mix of m4 and shell logic made the (x86) part problematic, and I never figured out how to escape that properly.