Small documentation fixes

Bukkit/src/main/java/com/plotsquared/bukkit/player/BukkitPlayer.java

@@ -164,7 +164,7 @@ public class BukkitPlayer extends PlotPlayer<Player> {
         }
     }
 
-    @Override public boolean hasPermission(final String permission) {
+    @Override public boolean hasPermission(@NotNull final String permission) {
         if (this.offline && EconHandler.getEconHandler() != null) {
             return EconHandler.getEconHandler().hasPermission(getName(), permission);
         }
@@ -231,7 +231,7 @@ public class BukkitPlayer extends PlotPlayer<Player> {
         return max;
     }
 
-    @Override public boolean isPermissionSet(final String permission) {
+    @Override public boolean isPermissionSet(@NotNull final String permission) {
         return this.player.isPermissionSet(permission);
     }
 

Core/src/main/java/com/plotsquared/core/command/CommandCaller.java

@@ -29,6 +29,10 @@ import com.plotsquared.core.configuration.Caption;
 import net.kyori.adventure.text.minimessage.Template;
 import org.jetbrains.annotations.NotNull;
 
+/**
+ * Any entity that is able to execute commands, receive messages & and have
+ * permission nodes
+ */
 public interface CommandCaller {
 
     /**
@@ -44,9 +48,22 @@ public interface CommandCaller {
      *
      * @param permission the name of the permission
      */
-    boolean hasPermission(String permission);
+    boolean hasPermission(@NotNull String permission);
 
-    boolean isPermissionSet(String permission);
+    /**
+     * Checks if this object contains an override for the specified
+     * permission, by fully qualified name
+     *
+     * @param permission Name of the permission
+     * @return true if the permission is set, otherwise false
+     */
+    boolean isPermissionSet(@NotNull String permission);
+
+    /**
+     * Get the type of the caller
+     *
+     * @return Caller type
+     */
+    @NotNull RequiredType getSuperCaller();
 
-    RequiredType getSuperCaller();
 }

Core/src/main/java/com/plotsquared/core/player/ConsolePlayer.java

@@ -99,11 +99,11 @@ public class ConsolePlayer extends PlotPlayer<Actor> {
         return 0;
     }
 
-    @Override public boolean hasPermission(String permission) {
+    @Override public boolean hasPermission(@NotNull String permission) {
         return true;
     }
 
-    @Override public boolean isPermissionSet(String permission) {
+    @Override public boolean isPermissionSet(@NotNull String permission) {
         return true;
     }
 
@@ -137,7 +137,7 @@ public class ConsolePlayer extends PlotPlayer<Actor> {
     @Override public void removeAttribute(String key) {
     }
 
-    @Override public RequiredType getSuperCaller() {
+    @Override @NotNull public RequiredType getSuperCaller() {
         return RequiredType.CONSOLE;
     }
 

Core/src/main/java/com/plotsquared/core/player/PlotPlayer.java

@@ -361,7 +361,7 @@ public abstract class PlotPlayer<P> implements CommandCaller, OfflinePlotPlayer,
         return PlotSquared.get().getApplicablePlotArea(getLocation());
     }
 
-    @Override public RequiredType getSuperCaller() {
+    @Override @NotNull public RequiredType getSuperCaller() {
         return RequiredType.PLAYER;
     }