Fix SortedSet using compare for equals (#4479)

Fix SortedSet using compare for equals

src/api/java/appeng/api/networking/energy/IAEPowerStorage.java

@@ -27,6 +27,7 @@ import javax.annotation.Nonnull;
 
 import appeng.api.config.AccessRestriction;
 import appeng.api.config.Actionable;
+import appeng.api.networking.IGrid;
 
 /**
  * Used to access information about AE's various power accepting blocks for
@@ -78,6 +79,10 @@ public interface IAEPowerStorage extends IEnergySource {
      * A higher value means it is more likely to be extracted from first, and less
      * likely to be inserted into first.
      * 
+     * The value needs to be constant once added to a {@link IGrid}. Should it ever
+     * need to be changed, it has to be removed from the grid, then update the
+     * value, and finally added back to the grid.
+     * 
      * This should never use {@link Integer#MIN_VALUE} or {@link Integer#MAX_VALUE}.
      * 
      * @return the priority for this storage

src/main/java/appeng/me/cache/EnergyGridCache.java

@@ -74,10 +74,13 @@ public class EnergyGridCache implements IEnergyGrid {
         return Double.compare(percent1, percent2);
     };
 
-    private static final Comparator<IAEPowerStorage> COMPARATOR_HIGHEST_PRIORITY_FIRST = (o1, o2) -> Integer
-            .compare(o2.getPriority(), o1.getPriority());
-    private static final Comparator<IAEPowerStorage> COMPARATOR_LOWEST_PRIORITY_FIRST = (o1, o2) -> Integer
-            .compare(o1.getPriority(), o2.getPriority());
+    private static final Comparator<IAEPowerStorage> COMPARATOR_HIGHEST_PRIORITY_FIRST = (o1, o2) -> {
+        final int cmp = Integer.compare(o2.getPriority(), o1.getPriority());
+        return cmp != 0 ? cmp : Integer.compare(System.identityHashCode(o2), System.identityHashCode(o1));
+    };
+
+    private static final Comparator<IAEPowerStorage> COMPARATOR_LOWEST_PRIORITY_FIRST = (o1,
+            o2) -> -COMPARATOR_HIGHEST_PRIORITY_FIRST.compare(o1, o2);
 
     private final NavigableSet<EnergyThreshold> interests = Sets.newTreeSet();
     private final double averageLength = 40.0;