protected static boolean equals(Object lhs, Object rhs) {
        return !(lhs == null && rhs != null) &&
               !(lhs != null && rhs == null) &&
                ((lhs == null || lhs.equals(rhs)));
    }
Returns whether or not two objects are equal, taking into account that either can be null.

@param lhs The left hand side of the comparison.
@param rhs The right hand side of the comparison.
@return True if both arguments are null or equal.
vespajlib/src/main/java/com/yahoo/vespa/objects/Identifiable.java