java.base/unix/native/libnet/net_util_md.h declares
    89 int NET_Writev(int s, const struct iovec * vector, int count);

but java.base/linux/native/libnet/linux_close.c defines
    389 int NET_WriteV(int s, const struct iovec * vector, int count) {
    390 BLOCKING_IO_RETURN_INT( s, writev(s, vector, count) );
    391 }

Note the capitalization of the "V" in "NET_Writev" versus "NET_WriteV".

Similarly in solaris_close.c aix_close.c, and bsd_close.c

I think the declaration should be changed to match the defintions. Or, if no one uses the function (in either spelling), then it should be removed.