Refactor FluidTankList and Filtered Handlers

src/main/java/gregtech/api/capability/IDualHandler.java

@@ -8,7 +8,7 @@ public interface IDualHandler {
 
     boolean hasItemHandlers();
 
-    IMultipleTankHandler getFluidTanks();
+    MultipleTankHandler getFluidTanks();
 
     IItemHandler getItemHandlers();
 }

src/main/java/gregtech/api/capability/IFilteredFluidContainer.java

@@ -2,26 +2,5 @@
 
 import net.minecraftforge.fluids.FluidStack;
 
-import org.jetbrains.annotations.Nullable;
-
-import java.util.Comparator;
-
-/**
- * Interface for fluid containers ({@link net.minecraftforge.fluids.IFluidTank IFluidTank} or
- * {@link net.minecraftforge.fluids.capability.IFluidHandler IFluidHandler}) associated with {@link IFilter}.
- */
-public interface IFilteredFluidContainer {
-
-    /**
-     * Compare logic for filtered instances.
-     */
-    Comparator<IFilteredFluidContainer> COMPARATOR = Comparator.nullsLast(
-            Comparator.comparing(IFilteredFluidContainer::getFilter, IFilter.FILTER_COMPARATOR));
-
-    /**
-     * @return instance of {@link IFilter} associated to this object, or {@code null} if there's no filter
-     *         associated.
-     */
-    @Nullable
-    IFilter<FluidStack> getFilter();
-}
+// for type safe casting
+public interface IFilteredFluidContainer extends IFilteredHandler<FluidStack> {}

src/main/java/gregtech/api/capability/IFilteredHandler.java

@@ -0,0 +1,25 @@
+package gregtech.api.capability;
+
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Comparator;
+
+/**
+ * Interface for fluid containers ({@link net.minecraftforge.fluids.IFluidTank IFluidTank} or
+ * {@link net.minecraftforge.fluids.capability.IFluidHandler IFluidHandler}) associated with {@link IFilter}.
+ */
+public interface IFilteredHandler<T> {
+
+    /**
+     * Compare logic for filtered instances.
+     */
+    Comparator<IFilteredHandler<?>> COMPARATOR = Comparator.nullsLast(
+            Comparator.comparing(IFilteredHandler::getFilter, IFilter.FILTER_COMPARATOR));
+
+    /**
+     * @return instance of {@link IFilter} associated to this object, or {@code null} if there's no filter
+     *         associated.
+     */
+    @Nullable
+    IFilter<T> getFilter();
+}

src/main/java/gregtech/api/capability/IFilteredItemContainer.java

@@ -0,0 +1,5 @@
+package gregtech.api.capability;
+
+import net.minecraft.item.ItemStack;
+
+public interface IFilteredItemContainer extends IFilteredHandler<ItemStack> {}