/**
* Why would this mission be invalid with the given unit?
*
* @param aiUnit The <code>AIUnit</code> to test.
* @return A reason why the mission would be invalid with the unit, or null if none found.
*/
private static String invalidMissionReason(AIUnit aiUnit) {
String reason = invalidAIUnitReason(aiUnit);
if (reason != null) return reason;
final Unit unit = aiUnit.getUnit();
return (!unit.canCarryTreasure())
? "unit-cannot-carry-treasure"
: (unit.getTreasureAmount() <= 0) ? "unit-treasure-nonpositive" : null;
}
