public boolean empty() {
        return lowest > highest;
    }
A version range.

A range consists of two 16-bit numbers: the lowest version which is accepted, and the highest.
Ranges are inclusive, meaning that both the lowest and the highest version are valid versions.
The only exception to this is the NONE range, which contains no versions at all.

Version ranges can be represented as strings.

A single supported version V is represented as "V".
A bounded range from A to B is represented as "A-B".
All versions greater than A is represented as "A+".
The NONE range is represented as the string "none".
generator/src/main/java/org/apache/kafka/message/Versions.java