Refused maintenance generation

- A chunk is refused while Folia world maintenance forbids mantle stages
- Such chunks no longer end up missing objects, caves, deposits or their REAL flag
- Refused chunks warn at most every 5 seconds
- The overworld mode no longer bypasses mantle stages

core/src/test/java/art/arcane/iris/generation/runtime/IrisEngineMaintenanceRefusalTest.java

@@ -0,0 +1,49 @@
+package art.arcane.iris.generation.runtime;
+
+import art.arcane.iris.world.IrisWorld;
+import art.arcane.volmlib.nativelib.terrain.NativeBiome;
+import art.arcane.volmlib.nativelib.terrain.NativeBlockState;
+import art.arcane.volmlib.util.hunk.Hunk;
+import org.junit.Test;
+
+import java.lang.reflect.Field;
+
+import static org.junit.Assert.assertThrows;
+import static org.junit.Assert.assertTrue;
+import static org.mockito.ArgumentMatchers.any;
+import static org.mockito.ArgumentMatchers.anyBoolean;
+import static org.mockito.ArgumentMatchers.anyInt;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.doCallRealMethod;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoInteractions;
+import static org.mockito.Mockito.when;
+
+public class IrisEngineMaintenanceRefusalTest {
+    @Test
+    @SuppressWarnings("unchecked")
+    public void maintenanceThatCannotRunMantleStagesRefusesTheChunkInsteadOfGeneratingIt() throws Exception {
+        IrisEngine engine = mock(IrisEngine.class);
+        EnginePlatformHooks hooks = mock(EnginePlatformHooks.class);
+        when(hooks.shouldRefuseGeneration(engine)).thenReturn(true);
+        Field platformHooks = IrisEngine.class.getDeclaredField("platformHooks");
+        platformHooks.setAccessible(true);
+        platformHooks.set(engine, hooks);
+        IrisWorld world = mock(IrisWorld.class);
+        when(world.name()).thenReturn("world");
+        when(engine.getWorld()).thenReturn(world);
+        doCallRealMethod().when(engine).generate(anyInt(), anyInt(), any(), any(), anyBoolean());
+        Hunk<NativeBlockState> blocks = mock(Hunk.class);
+        Hunk<NativeBiome> biomes = mock(Hunk.class);
+
+        GenerationSessionException refused = assertThrows(GenerationSessionException.class,
+                () -> engine.generate(32, 48, blocks, biomes, false));
+
+        assertTrue(refused.isExpectedTeardown());
+        verify(engine, never()).acquireGenerationLease(anyString());
+        verify(engine, never()).getMode();
+        verifyNoInteractions(blocks, biomes);
+    }
+}