Comment for UserMappingPasswordRequired in contrib/postgres_fdw

Hi,

While working on something else, I noticed $SUBJECT:

/*
* Return true if the password_required is defined and false for this user
* mapping, otherwise false. The mapping has been pre-validated.
*/
static bool
UserMappingPasswordRequired(UserMapping *user)
{
ListCell *cell;

foreach(cell, user->options)
{
DefElem *def = (DefElem *) lfirst(cell);

if (strcmp(def->defname, "password_required") == 0)
return defGetBoolean(def);
}

return true;
}

I think the former part of the comment should be: Return *false* if
the password_required is defined and false for this user mapping,
otherwise *true*.

Patch attached.

Best regards,
Etsuro Fujita