[core, weaver-pojo] Introduce NullableConfigEntry and pseudo entries during weaving

tweed5/core/src/main/java/de/siphalor/tweed5/core/api/entry/ConfigEntry.java

@@ -2,7 +2,6 @@ package de.siphalor.tweed5.core.api.entry;
 
 import de.siphalor.tweed5.core.api.container.ConfigContainer;
 import de.siphalor.tweed5.patchwork.api.Patchwork;
-import org.jspecify.annotations.NonNull;
 import org.jspecify.annotations.Nullable;
 
 import java.util.function.Consumer;
@@ -26,7 +25,7 @@ public interface ConfigEntry<T extends @Nullable Object> {
 	}
 
 	void visitInOrder(ConfigEntryVisitor visitor);
-	void visitInOrder(ConfigEntryValueVisitor visitor, @Nullable T value);
+	void visitInOrder(ConfigEntryValueVisitor visitor, T value);
 
-	T deepCopy(@NonNull T value);
+	T deepCopy(T value);
 }

tweed5/core/src/main/java/de/siphalor/tweed5/core/api/entry/NullableConfigEntry.java

@@ -0,0 +1,17 @@
+package de.siphalor.tweed5.core.api.entry;
+
+import org.jetbrains.annotations.Nullable;
+
+import java.util.function.Consumer;
+
+public interface NullableConfigEntry<T extends @Nullable Object> extends StructuredConfigEntry<T> {
+	String NON_NULL_KEY = ":nonNull";
+
+	@Override
+	default NullableConfigEntry<T> apply(Consumer<ConfigEntry<T>> function) {
+		StructuredConfigEntry.super.apply(function);
+		return this;
+	}
+
+	ConfigEntry<T> nonNullEntry();
+}

tweed5/core/src/main/java/de/siphalor/tweed5/core/impl/DefaultConfigContainer.java

@@ -16,7 +16,7 @@ import java.lang.reflect.Field;
 import java.lang.reflect.Modifier;
 import java.util.*;
 
-public class DefaultConfigContainer<T> implements ConfigContainer<T> {
+public class DefaultConfigContainer<T extends @Nullable Object> implements ConfigContainer<T> {
 	@Getter
 	private ConfigContainerSetupPhase setupPhase = ConfigContainerSetupPhase.EXTENSIONS_SETUP;
 	private final Set<Class<? extends TweedExtension>> requestedExtensions = new HashSet<>();

tweed5/core/src/main/java/de/siphalor/tweed5/core/impl/entry/NullableConfigEntryImpl.java

@@ -0,0 +1,52 @@
+package de.siphalor.tweed5.core.impl.entry;
+
+import de.siphalor.tweed5.core.api.container.ConfigContainer;
+import de.siphalor.tweed5.core.api.entry.BaseConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.ConfigEntryValueVisitor;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
+import lombok.Getter;
+import org.jetbrains.annotations.Nullable;
+
+import java.util.Collections;
+import java.util.Map;
+
+@Getter
+public class NullableConfigEntryImpl<T extends @Nullable Object> extends BaseConfigEntry<T> implements NullableConfigEntry<T> {
+	private final ConfigEntry<T> nonNullEntry;
+
+	public NullableConfigEntryImpl(
+			ConfigContainer<?> container,
+			Class<T> valueClass,
+			ConfigEntry<T> nonNullEntry
+	) {
+		super(container, valueClass);
+		this.nonNullEntry = nonNullEntry;
+	}
+
+	@Override
+	public Map<String, ConfigEntry<?>> subEntries() {
+		return Collections.singletonMap(NON_NULL_KEY, nonNullEntry);
+	}
+
+	@Override
+	public void visitInOrder(ConfigEntryValueVisitor visitor, T value) {
+		if (value != null) {
+			if (visitor.enterStructuredEntry(this, value)) {
+				if (visitor.enterStructuredSubEntry(NON_NULL_KEY, NON_NULL_KEY)) {
+					nonNullEntry.visitInOrder(visitor, value);
+					visitor.leaveStructuredSubEntry(NON_NULL_KEY, NON_NULL_KEY);
+				}
+				visitor.leaveStructuredEntry(this, value);
+			}
+		}
+	}
+
+	@Override
+	public T deepCopy(T value) {
+		if (value != null) {
+			return nonNullEntry.deepCopy(value);
+		}
+		return null;
+	}
+}

tweed5/default-extensions/src/test/java/de/siphalor/tweed5/defaultextensions/comment/impl/CommentExtensionImplTest.java

@@ -1,10 +1,12 @@
 package de.siphalor.tweed5.defaultextensions.comment.impl;
 
 import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
 import de.siphalor.tweed5.core.api.entry.SimpleConfigEntry;
 import de.siphalor.tweed5.core.api.extension.TweedExtension;
 import de.siphalor.tweed5.core.api.middleware.Middleware;
 import de.siphalor.tweed5.core.impl.DefaultConfigContainer;
+import de.siphalor.tweed5.core.impl.entry.NullableConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.SimpleConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.StaticMapCompoundConfigEntryImpl;
 import de.siphalor.tweed5.data.extension.api.ReadWriteExtension;
@@ -36,7 +38,7 @@ class CommentExtensionImplTest {
 
 	private DefaultConfigContainer<@NonNull Map<String, Object>> configContainer;
 	private CompoundConfigEntry<Map<String, Object>> rootEntry;
-	private SimpleConfigEntry<Integer> intEntry;
+	private NullableConfigEntry<Integer> intEntry;
 	private SimpleConfigEntry<String> stringEntry;
 	private SimpleConfigEntry<Long> noCommentEntry;
 
@@ -49,9 +51,13 @@ class CommentExtensionImplTest {
 		configContainer.registerExtensions(extraExtensions);
 		configContainer.finishExtensionSetup();
 
-		intEntry = new SimpleConfigEntryImpl<>(configContainer, Integer.class)
+		intEntry = new NullableConfigEntryImpl<>(
+				configContainer, Integer.class,
+				new SimpleConfigEntryImpl<>(configContainer, Integer.class)
 					.apply(entryReaderWriter(intReaderWriter()))
-				.apply(baseComment("It is an integer"));
+					.apply(baseComment("It is an integer")))
+				.apply(entryReaderWriter(nullableReaderWriter()))
+				.apply(baseComment("This is nullable"));
 		stringEntry = new SimpleConfigEntryImpl<>(configContainer, String.class)
 				.apply(entryReaderWriter(stringReaderWriter()))
 				.apply(baseComment("It is a string"));
@@ -80,7 +86,7 @@ class CommentExtensionImplTest {
 		configContainer.initialize();
 
 		CommentExtension commentExtension = configContainer.extension(CommentExtension.class).orElseThrow();
-		assertEquals("It is an integer", commentExtension.getFullComment(intEntry));
+		assertEquals("This is nullable", commentExtension.getFullComment(intEntry));
 		assertEquals("It is a string", commentExtension.getFullComment(stringEntry));
 		assertNull(commentExtension.getFullComment(noCommentEntry));
 	}
@@ -91,7 +97,7 @@ class CommentExtensionImplTest {
 		configContainer.initialize();
 
 		CommentExtension commentExtension = configContainer.extension(CommentExtension.class).orElseThrow();
-		assertEquals("The comment is:\nIt is an integer\nEND", commentExtension.getFullComment(intEntry));
+		assertEquals("The comment is:\nThis is nullable\nEND", commentExtension.getFullComment(intEntry));
 		assertEquals("The comment is:\nIt is a string\nEND", commentExtension.getFullComment(stringEntry));
 		assertEquals("The comment is:\n\nEND", commentExtension.getFullComment(noCommentEntry));
 	}
@@ -120,6 +126,7 @@ class CommentExtensionImplTest {
 				// This is the root value.
 				// It is the topmost value in the tree.
 				{
+				\t// This is nullable
 				\t// It is an integer
 				\tint: 123
 				\t// It is a string

tweed5/default-extensions/src/test/java/de/siphalor/tweed5/defaultextensions/patch/impl/PatchExtensionImplTest.java

@@ -5,6 +5,7 @@ import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
 import de.siphalor.tweed5.core.api.entry.ConfigEntry;
 import de.siphalor.tweed5.core.impl.DefaultConfigContainer;
 import de.siphalor.tweed5.core.impl.entry.CollectionConfigEntryImpl;
+import de.siphalor.tweed5.core.impl.entry.NullableConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.SimpleConfigEntryImpl;
 import de.siphalor.tweed5.core.impl.entry.StaticMapCompoundConfigEntryImpl;
 import de.siphalor.tweed5.data.extension.api.ReadWriteExtension;
@@ -51,28 +52,30 @@ class PatchExtensionImplTest {
 
 		var int1Entry = new SimpleConfigEntryImpl<>(configContainer, Integer.class)
 				.apply(entryReaderWriter(intReaderWriter()));
-		var int2Entry = new SimpleConfigEntryImpl<>(configContainer, Integer.class)
+		var int2Entry = new NullableConfigEntryImpl<>(
-				.apply(entryReaderWriter(
+				configContainer, Integer.class,
-						nullableReader(intReaderWriter()),
+				new SimpleConfigEntryImpl<>(configContainer, Integer.class)
-						nullableWriter(intReaderWriter())
+					.apply(entryReaderWriter(intReaderWriter())));
-				));
+		var listEntry = new NullableConfigEntryImpl<>(
-		var listEntry = new CollectionConfigEntryImpl<>(
+				configContainer,
+				(Class<List<Integer>>)(Class) List.class,
+				new CollectionConfigEntryImpl<>(
 						configContainer,
 						(Class<List<Integer>>)(Class) List.class,
 						ArrayList::new,
 						new SimpleConfigEntryImpl<>(configContainer, Integer.class)
 								.apply(entryReaderWriter(intReaderWriter()))
-		)
+				).apply(entryReaderWriter(collectionReaderWriter()))
-				.apply(entryReaderWriter(
+		).apply(entryReaderWriter(nullableReaderWriter()));
-						nullableReader(collectionReaderWriter()),
-						nullableWriter(collectionReaderWriter())
-				));
 
 		var nestedInt1Entry = new SimpleConfigEntryImpl<>(configContainer, Integer.class)
 				.apply(entryReaderWriter(intReaderWriter()));
 		var nestedInt2Entry = new SimpleConfigEntryImpl<>(configContainer, Integer.class)
 				.apply(entryReaderWriter(intReaderWriter()));
-		var compoundEntry = new StaticMapCompoundConfigEntryImpl<>(
+		var compoundEntry = new NullableConfigEntryImpl<>(
+				configContainer,
+				(Class<Map<String, Object>>)(Class) Map.class,
+				new StaticMapCompoundConfigEntryImpl<>(
 						configContainer,
 						(Class<Map<String, Object>>)(Class) Map.class,
 						HashMap::new,
@@ -80,11 +83,8 @@ class PatchExtensionImplTest {
 								entry("int1", nestedInt1Entry),
 								entry("int2", nestedInt2Entry)
 						))
-		)
+				).apply(entryReaderWriter(compoundReaderWriter()))
-				.apply(entryReaderWriter(
+		).apply(entryReaderWriter(nullableReaderWriter()));
-						nullableReader(compoundReaderWriter()),
-						nullableWriter(compoundReaderWriter())
-				));
 
 		rootEntry = new StaticMapCompoundConfigEntryImpl<>(
 				configContainer,

tweed5/default-extensions/src/test/java/de/siphalor/tweed5/defaultextensions/pather/api/PathTrackingDataReaderTest.java

@@ -1,6 +1,5 @@
 package de.siphalor.tweed5.defaultextensions.pather.api;
 
-import de.siphalor.tweed5.dataapi.api.TweedDataReadException;
 import de.siphalor.tweed5.dataapi.api.TweedDataReader;
 import de.siphalor.tweed5.dataapi.api.TweedDataToken;
 import de.siphalor.tweed5.dataapi.api.TweedDataTokens;

tweed5/serde-extension/src/main/java/de/siphalor/tweed5/data/extension/api/readwrite/TweedEntryReaderWriters.java

@@ -3,12 +3,14 @@ package de.siphalor.tweed5.data.extension.api.readwrite;
 import de.siphalor.tweed5.core.api.entry.CollectionConfigEntry;
 import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
 import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
 import de.siphalor.tweed5.data.extension.api.TweedEntryReader;
 import de.siphalor.tweed5.data.extension.api.TweedEntryWriter;
 import de.siphalor.tweed5.data.extension.impl.TweedEntryReaderWriterImpls;
 import lombok.AccessLevel;
 import lombok.NoArgsConstructor;
 import org.jspecify.annotations.NonNull;
+import org.jspecify.annotations.Nullable;
 
 import java.util.Collection;
 
@@ -51,12 +53,25 @@ public class TweedEntryReaderWriters {
 		return (TweedEntryReaderWriter<T, @NonNull ConfigEntry<T>>)(TweedEntryReaderWriter) TweedEntryReaderWriterImpls.ENUM_READER_WRITER;
 	}
 
-	public static <T, C extends ConfigEntry<T>> TweedEntryReader<T, C> nullableReader(TweedEntryReader<T, C> delegate) {
+	public static <T extends @Nullable Object> TweedEntryReaderWriter<T, NullableConfigEntry<T>> nullableReaderWriter() {
-		return new TweedEntryReaderWriterImpls.NullableReader<>(delegate);
+		//noinspection unchecked
+		return (TweedEntryReaderWriter<T, @NonNull NullableConfigEntry<T>>) (TweedEntryReaderWriter<?, ?>) TweedEntryReaderWriterImpls.NULLABLE_READER_WRITER;
 	}
 
+	/**
+	 * @deprecated You probably want to use {@link #nullableReaderWriter()} instead.
+	 */
+	@Deprecated
+	public static <T, C extends ConfigEntry<T>> TweedEntryReader<T, C> nullableReader(TweedEntryReader<T, C> delegate) {
+		return new TweedEntryReaderWriterImpls.FixedNullableReader<>(delegate);
+	}
+
+	/**
+	 * @deprecated You probably want to use {@link #nullableReaderWriter()} instead.
+	 */
+	@Deprecated
 	public static <T, C extends ConfigEntry<T>> TweedEntryWriter<T, C> nullableWriter(TweedEntryWriter<T, C> delegate) {
-		return new TweedEntryReaderWriterImpls.NullableWriter<>(delegate);
+		return new TweedEntryReaderWriterImpls.FixedNullableWriter<>(delegate);
 	}
 
 	public static <T, C extends Collection<T>> TweedEntryReaderWriter<C, CollectionConfigEntry<T, C>> collectionReaderWriter() {

tweed5/serde-extension/src/main/java/de/siphalor/tweed5/data/extension/impl/DefaultTweedEntryReaderWriterImplsProvider.java

@@ -4,6 +4,10 @@ import com.google.auto.service.AutoService;
 import de.siphalor.tweed5.data.extension.api.TweedEntryReader;
 import de.siphalor.tweed5.data.extension.api.TweedEntryWriter;
 import de.siphalor.tweed5.data.extension.api.TweedReaderWriterProvider;
+import de.siphalor.tweed5.data.extension.api.readwrite.TweedEntryReaderWriters;
+import lombok.RequiredArgsConstructor;
+
+import java.util.function.Function;
 
 import static de.siphalor.tweed5.data.extension.api.readwrite.TweedEntryReaderWriters.*;
 
@@ -39,22 +43,32 @@ public class DefaultTweedEntryReaderWriterImplsProvider implements TweedReaderWr
 		context.registerWriterFactory("tweed5.string", new StaticReaderWriterFactory<>(stringReaderWriter()));
 		context.registerReaderFactory("tweed5.enum", new StaticReaderWriterFactory<>(enumReaderWriter()));
 		context.registerWriterFactory("tweed5.enum", new StaticReaderWriterFactory<>(enumReaderWriter()));
+		context.registerReaderFactory("tweed5.nullable", new NullableReaderWriterFactory<>(
+				TweedEntryReaderWriters::nullableReader
+		));
+		context.registerWriterFactory("tweed5.nullable", new NullableReaderWriterFactory<>(
+				TweedEntryReaderWriters::nullableWriter
+		));
 		context.registerReaderFactory("tweed5.collection", new StaticReaderWriterFactory<>(collectionReaderWriter()));
 		context.registerWriterFactory("tweed5.collection", new StaticReaderWriterFactory<>(collectionReaderWriter()));
 		context.registerReaderFactory("tweed5.compound", new StaticReaderWriterFactory<>(compoundReaderWriter()));
 		context.registerWriterFactory("tweed5.compound", new StaticReaderWriterFactory<>(compoundReaderWriter()));
+	}
 
-		context.registerReaderFactory("tweed5.nullable", delegateReaders -> {
+	@RequiredArgsConstructor
-			if (delegateReaders.length != 1) {
+	private static class NullableReaderWriterFactory<T> implements ReaderWriterFactory<T> {
-				throw new IllegalArgumentException("Nullable reader requires a single delegate argument, got " + delegateReaders.length);
+		private final Function<T, T> delegateBasedFactory;
-			}
+
-			return nullableReader(delegateReaders[0]);
+		@Override
-		});
+		public T create(T... delegateReaderWriters) {
-		context.registerWriterFactory("tweed5.nullable", delegateWriters -> {
+			if (delegateReaderWriters.length == 0) {
-			if (delegateWriters.length != 1) {
+				//noinspection unchecked
-				throw new IllegalArgumentException("Nullable writer requires a single delegate argument, got " + delegateWriters.length);
+				return (T) TweedEntryReaderWriters.nullableReaderWriter();
-			}
+			} else if (delegateReaderWriters.length == 1) {
-			return nullableWriter(delegateWriters[0]);
+				return delegateBasedFactory.apply(delegateReaderWriters[0]);
-		});
+			} else {
+				throw new IllegalArgumentException("Nullable readers and writers may have only one or zero delegates");
+			}
+		}
 	}
 }

tweed5/serde-extension/src/main/java/de/siphalor/tweed5/data/extension/impl/TweedEntryReaderWriterImpls.java

@@ -3,6 +3,7 @@ package de.siphalor.tweed5.data.extension.impl;
 import de.siphalor.tweed5.core.api.entry.CollectionConfigEntry;
 import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
 import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
 import de.siphalor.tweed5.data.extension.api.*;
 import de.siphalor.tweed5.data.extension.api.readwrite.TweedEntryReaderWriter;
 import de.siphalor.tweed5.dataapi.api.*;
@@ -28,13 +29,48 @@ public class TweedEntryReaderWriterImpls {
 	public static final TweedEntryReaderWriter<String, ConfigEntry<String>> STRING_READER_WRITER = new PrimitiveReaderWriter<>(TweedDataToken::readAsString, TweedDataVisitor::visitString);
 	public static final TweedEntryReaderWriter<Enum<?>, ConfigEntry<Enum<?>>> ENUM_READER_WRITER = new EnumReaderWriter<>();
 
+	public static final TweedEntryReaderWriter<Object, NullableConfigEntry<Object>> NULLABLE_READER_WRITER = new NullableReaderWriter<>();
 	public static final TweedEntryReaderWriter<Collection<Object>, CollectionConfigEntry<Object, Collection<Object>>> COLLECTION_READER_WRITER = new CollectionReaderWriter<>();
 	public static final TweedEntryReaderWriter<Object, CompoundConfigEntry<Object>> COMPOUND_READER_WRITER = new CompoundReaderWriter<>();
 
 	public static final TweedEntryReaderWriter<Object, ConfigEntry<Object>> NOOP_READER_WRITER = new NoopReaderWriter();
 
+	public static class NullableReaderWriter<T extends @Nullable Object> implements TweedEntryReaderWriter<T, NullableConfigEntry<T>> {
+		@Override
+		public T read(TweedDataReader reader, NullableConfigEntry<T> entry, TweedReadContext context)
+				throws TweedEntryReadException {
+			try {
+				if (reader.peekToken().isNull()) {
+					reader.readToken();
+					return null;
+				}
+			} catch (TweedDataReadException e) {
+				throw new TweedEntryReadException(e, context);
+			}
+
+			TweedEntryReader<T, ConfigEntry<T>> nonNullReader = context.readWriteExtension().getReaderChain(entry.nonNullEntry());
+			return nonNullReader.read(reader, entry.nonNullEntry(), context);
+		}
+
+		@Override
+		public void write(
+				TweedDataVisitor writer,
+				@Nullable T value,
+				NullableConfigEntry<T> entry,
+				TweedWriteContext context
+		) throws TweedEntryWriteException, TweedDataWriteException {
+			if (value == null) {
+				writer.visitNull();
+			} else {
+				TweedEntryWriter<T, ConfigEntry<T>> nonNullWriter = context.readWriteExtension().getWriterChain(entry.nonNullEntry());
+				nonNullWriter.write(writer, value, entry.nonNullEntry(), context);
+			}
+		}
+	}
+
+	@Deprecated
 	@RequiredArgsConstructor
-	public static class NullableReader<T extends @Nullable Object, C extends ConfigEntry<T>> implements TweedEntryReader<T, C> {
+	public static class FixedNullableReader<T extends @Nullable Object, C extends ConfigEntry<T>> implements TweedEntryReader<T, C> {
 		private final TweedEntryReader<T, C> delegate;
 
 		@Override
@@ -51,8 +87,9 @@ public class TweedEntryReaderWriterImpls {
 		}
 	}
 
+	@Deprecated
 	@RequiredArgsConstructor
-	public static class NullableWriter<T extends @Nullable Object, C extends ConfigEntry<T>> implements TweedEntryWriter<T, C> {
+	public static class FixedNullableWriter<T extends @Nullable Object, C extends ConfigEntry<T>> implements TweedEntryWriter<T, C> {
 		private final TweedEntryWriter<T, C> delegate;
 
 		@Override

tweed5/weaver-pojo-serde-extension/src/main/java/de/siphalor/tweed5/weaver/pojoext/serde/api/auto/AutoReadWritePojoWeavingProcessor.java

@@ -2,10 +2,12 @@ package de.siphalor.tweed5.weaver.pojoext.serde.api.auto;
 
 import de.siphalor.tweed5.core.api.container.ConfigContainer;
 import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
 import de.siphalor.tweed5.data.extension.api.ReadWriteExtension;
 import de.siphalor.tweed5.data.extension.api.TweedEntryReader;
 import de.siphalor.tweed5.data.extension.api.TweedEntryWriter;
 import de.siphalor.tweed5.data.extension.api.TweedReaderWriterProvider;
+import de.siphalor.tweed5.data.extension.api.readwrite.TweedEntryReaderWriters;
 import de.siphalor.tweed5.data.extension.impl.TweedEntryReaderWriterImpls;
 import de.siphalor.tweed5.patchwork.api.Patchwork;
 import de.siphalor.tweed5.patchwork.api.PatchworkPartAccess;
@@ -113,6 +115,15 @@ public class AutoReadWritePojoWeavingProcessor implements TweedPojoWeavingExtens
 
 	@Override
 	public <T> void afterWeaveEntry(ActualType<T> valueType, ConfigEntry<T> configEntry, WeavingContext context) {
+		if (configEntry instanceof NullableConfigEntry) {
+			readWriteExtension.setEntryReaderWriter(
+					configEntry,
+					TweedEntryReaderWriters.nullableReaderWriter(),
+					TweedEntryReaderWriters.nullableReaderWriter()
+			);
+			return;
+		}
+
 		assert customDataAccess != null;
 		CustomData customData = context.extensionsData().get(customDataAccess);
 		if (customData == null || customData.mappings().isEmpty()) {

tweed5/weaver-pojo-serde-extension/src/main/java/de/siphalor/tweed5/weaver/pojoext/serde/api/nullable/AutoNullableReadWriteBehavior.java

@@ -5,6 +5,10 @@ import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
 
+/**
+ * @see AutoNullableReadWritePojoWeavingProcessor
+ */
+@Deprecated
 @Retention(RetentionPolicy.RUNTIME)
 @Target({ElementType.TYPE, ElementType.ANNOTATION_TYPE})
 public @interface AutoNullableReadWriteBehavior {

tweed5/weaver-pojo-serde-extension/src/main/java/de/siphalor/tweed5/weaver/pojoext/serde/api/nullable/AutoNullableReadWritePojoWeavingProcessor.java

@@ -17,6 +17,11 @@ import org.jspecify.annotations.Nullable;
 
 import java.lang.annotation.Annotation;
 
+/**
+ * @deprecated The recommended approach is to use {@link de.siphalor.tweed5.weaver.pojo.api.weaving.NullablePojoWeaver}
+ * and set @{@link Nullable} on all nullable entries.
+ */
+@Deprecated
 public class AutoNullableReadWritePojoWeavingProcessor implements TweedPojoWeavingExtension {
 	private final ReadWriteExtension readWriteExtension;
 	private @Nullable PatchworkPartAccess<CustomData> customDataAccess;
@@ -71,14 +76,14 @@ public class AutoNullableReadWritePojoWeavingProcessor implements TweedPojoWeavi
 			if (definedEntryReader != null) {
 				readWriteExtension.setEntryReader(
 						configEntry,
-						new TweedEntryReaderWriterImpls.NullableReader<>(definedEntryReader)
+						new TweedEntryReaderWriterImpls.FixedNullableReader<>(definedEntryReader)
 				);
 			}
 			val definedEntryWriter = readWriteExtension.getDefinedEntryWriter(configEntry);
 			if (definedEntryWriter != null) {
 				readWriteExtension.setEntryWriter(
 						configEntry,
-						new TweedEntryReaderWriterImpls.NullableWriter<>(definedEntryWriter)
+						new TweedEntryReaderWriterImpls.FixedNullableWriter<>(definedEntryWriter)
 				);
 			}
 		}

tweed5/weaver-pojo-serde-extension/src/main/java/de/siphalor/tweed5/weaver/pojoext/serde/api/nullable/AutoReadWriteNullability.java

@@ -1,5 +1,9 @@
 package de.siphalor.tweed5.weaver.pojoext.serde.api.nullable;
 
+/**
+ * @see AutoNullableReadWriteBehavior
+ */
+@Deprecated
 public enum AutoReadWriteNullability {
 	NON_NULL,
 	NULLABLE,

tweed5/weaver-pojo-serde-extension/src/test/java/de/siphalor/tweed5/weaver/pojoext/serde/api/auto/AutoReadWritePojoWeavingProcessorTest.java

@@ -4,6 +4,7 @@ import de.siphalor.tweed5.core.api.container.ConfigContainer;
 import de.siphalor.tweed5.core.api.entry.CollectionConfigEntry;
 import de.siphalor.tweed5.core.api.entry.CompoundConfigEntry;
 import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.api.entry.NullableConfigEntry;
 import de.siphalor.tweed5.data.extension.api.ReadWriteExtension;
 import de.siphalor.tweed5.data.extension.api.readwrite.TweedEntryReaderWriter;
 import de.siphalor.tweed5.data.extension.impl.TweedEntryReaderWriterImpls;
@@ -12,9 +13,11 @@ import de.siphalor.tweed5.weaver.pojo.api.annotation.CompoundWeaving;
 import de.siphalor.tweed5.weaver.pojo.api.annotation.DefaultWeavingExtensions;
 import de.siphalor.tweed5.weaver.pojo.api.annotation.PojoWeaving;
 import de.siphalor.tweed5.weaver.pojo.api.annotation.PojoWeavingExtension;
+import de.siphalor.tweed5.weaver.pojo.api.weaving.NullablePojoWeaver;
 import de.siphalor.tweed5.weaver.pojo.impl.weaving.TweedPojoWeaverBootstrapper;
 import lombok.Data;
 import org.jspecify.annotations.NullUnmarked;
+import org.jspecify.annotations.Nullable;
 import org.junit.jupiter.api.BeforeEach;
 import org.junit.jupiter.api.Test;
 
@@ -24,6 +27,7 @@ import java.util.List;
 
 import static de.siphalor.tweed5.data.extension.api.ReadWriteExtension.write;
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.InstanceOfAssertFactories.type;
 
 @NullUnmarked
 class AutoReadWritePojoWeavingProcessorTest {
@@ -50,7 +54,11 @@ class AutoReadWritePojoWeavingProcessorTest {
 		assertReaderAndWriter(primitiveIntEntry, TweedEntryReaderWriterImpls.INT_READER_WRITER);
 
 		var boxedLongEntry = rootEntry.subEntries().get("boxedLong");
-		assertReaderAndWriter(boxedLongEntry, TweedEntryReaderWriterImpls.LONG_READER_WRITER);
+		assertReaderAndWriter(boxedLongEntry, TweedEntryReaderWriterImpls.NULLABLE_READER_WRITER);
+		assertThat(boxedLongEntry).asInstanceOf(type(NullableConfigEntry.class))
+				.satisfies(nullableEntry -> assertReaderAndWriter(
+						nullableEntry.nonNullEntry(), TweedEntryReaderWriterImpls.LONG_READER_WRITER
+				));
 
 		var stringEntry = rootEntry.subEntries().get("string");
 		assertReaderAndWriter(stringEntry, TweedEntryReaderWriterImpls.STRING_READER_WRITER);
@@ -115,6 +123,7 @@ class AutoReadWritePojoWeavingProcessorTest {
 	}
 
 	@PojoWeaving(extensions = ReadWriteExtension.class)
+	@PojoWeavingExtension(NullablePojoWeaver.class)
 	@DefaultWeavingExtensions
 	@PojoWeavingExtension(AutoReadWritePojoWeavingProcessor.class)
 	@DefaultReadWriteMappings
@@ -122,7 +131,7 @@ class AutoReadWritePojoWeavingProcessorTest {
 	@Data
 	public static class AnnotatedConfig {
 		private int primitiveInt;
-		private Long boxedLong;
+		private @Nullable Long boxedLong;
 		private String string;
 		private List<@CompoundWeaving Nested> nesteds;
 	}

tweed5/weaver-pojo-serde-extension/src/test/java/de/siphalor/tweed5/weaver/pojoext/serde/api/nullable/AutoNullableReadWritePojoWeavingProcessorTest.java

@@ -85,22 +85,22 @@ class AutoNullableReadWritePojoWeavingProcessorTest {
 
 	private void assertNullableReader(ConfigEntry<?> entry) {
 		assertThat(readWriteExtension.getDefinedEntryReader(entry))
-				.isInstanceOf(TweedEntryReaderWriterImpls.NullableReader.class);
+				.isInstanceOf(TweedEntryReaderWriterImpls.FixedNullableReader.class);
 	}
 
 	private void assertNonNullableReader(ConfigEntry<?> entry) {
 		assertThat(readWriteExtension.getDefinedEntryReader(entry))
-				.isNotInstanceOf(TweedEntryReaderWriterImpls.NullableReader.class);
+				.isNotInstanceOf(TweedEntryReaderWriterImpls.FixedNullableReader.class);
 	}
 
 	private void assertNullableWriter(ConfigEntry<?> entry) {
 		assertThat(readWriteExtension.getDefinedEntryWriter(entry))
-				.isInstanceOf(TweedEntryReaderWriterImpls.NullableWriter.class);
+				.isInstanceOf(TweedEntryReaderWriterImpls.FixedNullableWriter.class);
 	}
 
 	private void assertNonNullableWriter(ConfigEntry<?> entry) {
 		assertThat(readWriteExtension.getDefinedEntryWriter(entry))
-				.isNotInstanceOf(TweedEntryReaderWriterImpls.NullableWriter.class);
+				.isNotInstanceOf(TweedEntryReaderWriterImpls.FixedNullableWriter.class);
 	}
 
 	@SneakyThrows

tweed5/weaver-pojo/src/main/java/de/siphalor/tweed5/weaver/pojo/api/weaving/NullablePojoWeaver.java

@@ -0,0 +1,66 @@
+package de.siphalor.tweed5.weaver.pojo.api.weaving;
+
+import de.siphalor.tweed5.core.api.entry.ConfigEntry;
+import de.siphalor.tweed5.core.impl.entry.NullableConfigEntryImpl;
+import de.siphalor.tweed5.patchwork.api.Patchwork;
+import de.siphalor.tweed5.patchwork.api.PatchworkPartAccess;
+import de.siphalor.tweed5.typeutils.api.type.ActualType;
+import lombok.AllArgsConstructor;
+import lombok.Setter;
+import org.jspecify.annotations.Nullable;
+
+import java.lang.annotation.Annotation;
+import java.util.Locale;
+
+public class NullablePojoWeaver implements TweedPojoWeavingExtension {
+	private @Nullable PatchworkPartAccess<CustomData> customDataAccess;
+
+	@Override
+	public void setup(SetupContext context) {
+		customDataAccess = context.registerWeavingContextExtensionData(CustomData.class);
+	}
+
+	@Override
+	public <T> void beforeWeaveEntry(ActualType<T> valueType, Patchwork extensionsData, ProtoWeavingContext context) {
+		assert customDataAccess != null;
+
+		Boolean nullable = null;
+		for (Annotation annotation : valueType.getAnnotations()) {
+			String annotationName = annotation.annotationType().getSimpleName().toLowerCase(Locale.ROOT);
+			switch (annotationName) {
+				case "nullable":
+					nullable = true;
+					break;
+				case "nonnull":
+				case "notnull":
+					nullable = false;
+					break;
+			}
+		}
+
+		extensionsData.set(customDataAccess, new CustomData(Boolean.TRUE.equals(nullable)));
+	}
+
+	@Override
+	public @Nullable <T> ConfigEntry<T> weaveEntry(ActualType<T> valueType, WeavingContext context) {
+		assert customDataAccess != null;
+
+		CustomData customData = context.extensionsData().get(customDataAccess);
+		if (customData == null || !customData.nullable) {
+			return null;
+		}
+
+		customData.nullable(false);
+		return new NullableConfigEntryImpl<>(
+				context.configContainer(),
+				valueType.declaredType(),
+				context.weavePseudoEntry(context, "nonNull", context.extensionsData())
+		);
+	}
+
+	@AllArgsConstructor
+	@Setter
+	private static class CustomData {
+		private boolean nullable;
+	}
+}

tweed5/weaver-pojo/src/main/java/de/siphalor/tweed5/weaver/pojo/api/weaving/WeavingContext.java

@@ -20,6 +20,8 @@ public class WeavingContext {
 	WeavingFn weavingFunction;
 	ConfigContainer<?> configContainer;
 	String[] path;
+	ActualType<?> valueType;
+	boolean isPseudo;
 	Patchwork extensionsData;
 	AnnotatedElement annotations;
 
@@ -27,7 +29,12 @@ public class WeavingContext {
 		return weavingFunction.weaveEntry(valueType, extensionsData, context);
 	}
 
+	public <T> ConfigEntry<T> weavePseudoEntry(WeavingContext parentContext, String pseudoEntryName, Patchwork extensionsData) {
+		return weavingFunction.weavePseudoEntry(parentContext, pseudoEntryName, extensionsData);
+	}
+
 	public interface WeavingFn {
 		<T> ConfigEntry<T> weaveEntry(ActualType<T> valueType, Patchwork extensionsData, ProtoWeavingContext context);
+		<T> ConfigEntry<T> weavePseudoEntry(WeavingContext parentContext, String pseudoEntryName, Patchwork extensionsData);
 	}
 }

tweed5/weaver-pojo/src/main/java/de/siphalor/tweed5/weaver/pojo/impl/entry/StaticPojoCompoundConfigEntry.java

@@ -79,7 +79,7 @@ public class StaticPojoCompoundConfigEntry<T> extends BaseConfigEntry<T> impleme
 	}
 
 	@Override
-	public void visitInOrder(ConfigEntryValueVisitor visitor, @Nullable T value) {
+	public void visitInOrder(ConfigEntryValueVisitor visitor, T value) {
 		if (visitor.enterStructuredEntry(this, value)) {
 			subEntries.forEach((key, entry) -> {
 				if (visitor.enterStructuredSubEntry(key, key)) {

tweed5/weaver-pojo/src/main/java/de/siphalor/tweed5/weaver/pojo/impl/weaving/TweedPojoWeaverBootstrapper.java

@@ -33,6 +33,21 @@ public class TweedPojoWeaverBootstrapper<T> {
 	private final AnnotatedElement pojoAnnotations;
 	private final ConfigContainer<T> configContainer;
 	private final Collection<TweedPojoWeavingExtension> weavingExtensions;
+	private final WeavingContext.WeavingFn weavingContextFn = new WeavingContext.WeavingFn() {
+		@Override
+		public <U> ConfigEntry<U> weaveEntry(
+				ActualType<U> valueType,
+				Patchwork extensionsData,
+				ProtoWeavingContext context
+		) {
+			return TweedPojoWeaverBootstrapper.this.weaveEntry(valueType, extensionsData, context);
+		}
+
+		@Override
+		public <U> ConfigEntry<U> weavePseudoEntry(WeavingContext parentContext, String pseudoEntryName, Patchwork extensionsData) {
+			return TweedPojoWeaverBootstrapper.this.weavePseudoEntry(parentContext, pseudoEntryName, extensionsData);
+		}
+	};
 	@Nullable
 	private PatchworkFactory weavingExtensionsPatchworkFactory;
 
@@ -119,18 +134,19 @@ public class TweedPojoWeaverBootstrapper<T> {
 	}
 
 	private <U> ConfigEntry<U> weaveEntry(
-			ActualType<U> dataClass,
+			ActualType<U> valueType,
 			Patchwork extensionsData,
 			ProtoWeavingContext protoContext
 	) {
 		extensionsData = extensionsData.copy();
 
-		runBeforeWeaveHooks(dataClass, extensionsData, protoContext);
+		runBeforeWeaveHooks(valueType, extensionsData, protoContext);
 
 		WeavingContext context = WeavingContext.builder()
 				.parent(protoContext.parent())
-				.weavingFunction(this::weaveEntry)
+				.weavingFunction(weavingContextFn)
 				.configContainer(configContainer)
+				.valueType(valueType)
 				.path(protoContext.path())
 				.extensionsData(extensionsData)
 				.annotations(new AnnotationInheritanceAwareAnnotatedElement(protoContext.annotations()))
@@ -138,17 +154,70 @@ public class TweedPojoWeaverBootstrapper<T> {
 
 		for (TweedPojoWeavingExtension weavingExtension : weavingExtensions) {
 			try {
-				ConfigEntry<U> configEntry = weavingExtension.weaveEntry(dataClass, context);
+				ConfigEntry<U> configEntry = weavingExtension.weaveEntry(valueType, context);
 				if (configEntry != null) {
-					runAfterWeaveHooks(dataClass, configEntry, context);
+					runAfterWeaveHooks(valueType, configEntry, context);
 					return configEntry;
 				}
 			} catch (Exception e) {
-				log.error("Failed to run Tweed POJO weaver (" + weavingExtension.getClass().getName() + ")", e);
+				log.error(
+						"Failed to run Tweed POJO weaver (" + weavingExtension.getClass().getName() + ")"
+								+ " for entry at " + Arrays.toString(context.path()),
+						e
+				);
 			}
 		}
 
-		throw new PojoWeavingException("Failed to weave " + dataClass + ": No matching weavers found");
+		throw new PojoWeavingException(
+				"Failed to weave entry for " + valueType + " at " + Arrays.toString(context.path())
+						+ ": No matching weavers found"
+		);
+	}
+
+	private <U> ConfigEntry<U> weavePseudoEntry(
+			WeavingContext parentContext,
+			String pseudoEntryName,
+			Patchwork extensionsData
+	) {
+		extensionsData = extensionsData.copy();
+
+		//noinspection unchecked
+		ActualType<U> valueType = (ActualType<U>) parentContext.valueType();
+
+		String[] path = Arrays.copyOf(parentContext.path(), parentContext.path().length + 1);
+		path[path.length - 1] = ":" + pseudoEntryName;
+
+		WeavingContext context = WeavingContext.builder()
+				.parent(parentContext)
+				.weavingFunction(weavingContextFn)
+				.configContainer(configContainer)
+				.path(path)
+				.valueType(parentContext.valueType())
+				.isPseudo(true)
+				.extensionsData(extensionsData)
+				.annotations(parentContext.annotations())
+				.build();
+
+		for (TweedPojoWeavingExtension weavingExtension : weavingExtensions) {
+			try {
+				ConfigEntry<U> configEntry = weavingExtension.weaveEntry(valueType, context);
+				if (configEntry != null) {
+					runAfterWeaveHooks(valueType, configEntry, context);
+					return configEntry;
+				}
+			} catch (Exception e) {
+				log.error(
+						"Failed to run Tweed POJO weaver (" + weavingExtension.getClass().getName() + ")"
+								+ " for pseudo entry at " + Arrays.toString(context.path()),
+						e
+				);
+			}
+		}
+
+		throw new PojoWeavingException(
+				"Failed to weave pseudo entry for " + valueType + " at " + Arrays.toString(context.path())
+						+ ": No matching weavers found"
+		);
 	}
 
 	private <U> void runBeforeWeaveHooks(

tweed5/weaver-pojo/src/test/java/de/siphalor/tweed5/weaver/pojo/api/weaving/CompoundPojoWeaverTest.java

@@ -7,10 +7,11 @@ import de.siphalor.tweed5.patchwork.api.Patchwork;
 import de.siphalor.tweed5.patchwork.api.PatchworkFactory;
 import de.siphalor.tweed5.typeutils.api.type.ActualType;
 import de.siphalor.tweed5.weaver.pojo.api.annotation.CompoundWeaving;
-import org.jspecify.annotations.NullUnmarked;
+import org.jetbrains.annotations.Nullable;
 import org.junit.jupiter.api.Test;
 
 import java.util.Objects;
+import java.util.concurrent.atomic.AtomicReference;
 
 import static de.siphalor.tweed5.weaver.pojo.test.ConfigEntryAssertions.isCompoundEntryForClassWith;
 import static de.siphalor.tweed5.weaver.pojo.test.ConfigEntryAssertions.isSimpleEntryForClass;
@@ -18,7 +19,6 @@ import static org.assertj.core.api.Assertions.assertThat;
 import static org.mockito.Mockito.mock;
 
 @SuppressWarnings("unused")
-@NullUnmarked
 class CompoundPojoWeaverTest {
 
 	@Test
@@ -30,8 +30,8 @@ class CompoundPojoWeaverTest {
 
 		PatchworkFactory weavingContextExtensionDataFactory = weavingContextExtensionDataFactoryBuilder.build();
 
-		WeavingContext weavingContext = WeavingContext.builder()
+		AtomicReference<WeavingContext.@Nullable WeavingFn> weavingFunction = new AtomicReference<>();
-				.weavingFunction(new WeavingContext.WeavingFn() {
+		weavingFunction.set(new WeavingContext.WeavingFn() {
 			@Override
 			public <T> ConfigEntry<T> weaveEntry(
 					ActualType<T> valueType,
@@ -43,14 +43,27 @@ class CompoundPojoWeaverTest {
 						.annotations(valueType)
 						.extensionsData(extensionsData.copy())
 						.path(protoContext.path())
-								.weavingFunction(protoContext.parent()::weaveEntry)
+						.weavingFunction(Objects.requireNonNull(weavingFunction.get()))
 						.build();
 				return Objects.requireNonNullElseGet(
 						compoundWeaver.weaveEntry(valueType, context),
 						() -> new SimpleConfigEntryImpl<>(context.configContainer(), valueType.declaredType())
 				);
 			}
-				})
+
+			@Override
+			public <T> ConfigEntry<T> weavePseudoEntry(
+					WeavingContext parentContext,
+					String pseudoEntryName,
+					Patchwork extensionsData
+			) {
+				assert false;
+				return null;
+			}
+		});
+
+		WeavingContext weavingContext = WeavingContext.builder()
+				.weavingFunction(Objects.requireNonNull(weavingFunction.get()))
 				.extensionsData(weavingContextExtensionDataFactory.create())
 				.annotations(Compound.class)
 				.path(new String[0])