@Override
    public int hashCode() {
        int hashCode = this.hashCode;
        if (hashCode == 0) {
            hashCode = comparisonStr.hashCode();
            if (hashCode == 0) {
                hashCode = 1;
            }

            this.hashCode = hashCode;
        }

        return hashCode;
    }
Returns the port group this {@link ServerPort} belongs to, or {@code 0} if this {@link ServerPort}
doesn't belong to any port group.
core/src/main/java/com/linecorp/armeria/server/ServerPort.java