@EventHandler
public void onDied (PlayerDiedEvent e ) {
    Player player = e. getPlayer ( ) ;
    DamageRecorder recorder = e. getRecorder ( ) ;
       
    // If the player last received damage from a player for more than 10 seconds or the player died unnaturally, the killer will be null
    Player killer = e. getKiller ( ) ;
}

@EventHandler
public void onPlayerDamageByPlayer (PlayerDamageByPlayerEvent e ) {
    Player suspect = e. getSuspect ( ) ;
    Player victim = e. getPlayer ( ) ;
}

public void testMethod ( ) {
    Player player = ... ;
    DamageRecorder recorder = ... ;

    // Damage a player at specified damage (Not physical damage, just record)
    recorder. damage (player, 1.5 ) ;

    // Get the killer of the player.
    // If player is not dead, it will throw IllegalStateException
    // If no one damage him, it will return null
    Player killer = recorder. getKiller ( ) ;

    // Get the assists of the player (not including killer)
    // If player is not dead, it will throw IllegalStateException
    // If no one damage him except the killer, or beside the killer, it will return null
    List <Player > assists = recorder. getAssists ( ) ;

    // Get the total damage of the player got
    double totalDamage = recorder. getTotalDamage ( ) ;

    // Get the damage caused by the specified player to the player
    double damage = recorder. getTotalDamage (killer ) ;

    // Make the player die (Not physical die, just record)
    recorder. die ( ) ;

    // Get whether the player is dead
    boolean died = recorder. isDied ( ) ;

    // Get the timestamp of the last time this player took damage
    long lastDamageTime = recorder. getLastDamageTime ( ) ;
}

public class YourCustomDurationCalculator implements DurationCalculator {
    @Override
    public int calculate (Player suspect ) {
        int duration = Your calculation logic... ;
        return duration ;
    }
}

CombatManager. setDurationCalculator ( new YourCustomDurationCalculator ( ) ) ;

public void testMethod ( ) {
    Player player = ... ;
       
    // Check if a player is in combat
    boolean combat = CombatManager. isInCombat (player ) ;
       
    // Reset a player's combat record
    CombatManager. resetCombat (player ) ;
       
    // Get the CombatInfo of the player
    CombatInfo info = CombatManager. getCombatInfo (player ) ;
}

public void testMethod ( ) {
    Player player = ... ;

    // Get CombatInfo
    CombatInfo info = CombatManager. getCombatInfo (player ) ;

    // Get the DamageRecorder of a player
    DamageRecorder recorder = info. getRecorder ( ) ;

    // Attack a player (Not physical attack, just record)
    info. attack (VICTIM, 2 ) ;
}