Polish "Add GraalVM native JSON configuration generation"

See gh-28131

spring-core/src/main/java/org/springframework/aot/nativex/BasicJsonWriter.java

@@ -0,0 +1,297 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.io.IOException;
+import java.io.Writer;
+import java.util.Iterator;
+import java.util.List;
+import java.util.Map;
+import java.util.function.Consumer;
+
+/**
+ * Very basic json writer for the purposes of translating runtime hints to native
+ * configuration.
+ *
+ * @author Stephane Nicoll
+ */
+class BasicJsonWriter {
+
+	private final IndentingWriter writer;
+
+	/**
+	 * Create a new instance with the specified indent value.
+	 * @param writer the writer to use
+	 * @param singleIndent the value of one indent
+	 */
+	public BasicJsonWriter(Writer writer, String singleIndent) {
+		this.writer = new IndentingWriter(writer, singleIndent);
+	}
+
+	/**
+	 * Create a new instance using two whitespaces for the indent.
+	 * @param writer the writer to use
+	 */
+	public BasicJsonWriter(Writer writer) {
+		this(writer, "  ");
+	}
+
+
+	/**
+	 * Write an object with the specified attributes. Each attribute is
+	 * written according to its value type:
+	 * <ul>
+	 * <li>Map: write the value as a nested object</li>
+	 * <li>List: write the value as a nested array</li>
+	 * <li>Otherwise, write a single value</li>
+	 * </ul>
+	 * @param attributes the attributes of the object
+	 */
+	public void writeObject(Map<String, Object> attributes) {
+		writeObject(attributes, true);
+	}
+
+	/**
+	 * Write an array with the specified items. Each item in the
+	 * list is written either as a nested object or as an attribute
+	 * depending on its type.
+	 * @param items the items to write
+	 * @see #writeObject(Map)
+	 */
+	public void writeArray(List<?> items) {
+		writeArray(items, true);
+	}
+
+	private void writeObject(Map<String, Object> attributes, boolean newLine) {
+		if (attributes.isEmpty()) {
+			this.writer.print("{ }");
+		}
+		else {
+			this.writer.println("{").indented(writeAll(attributes.entrySet().iterator(),
+					entry -> writeAttribute(entry.getKey(), entry.getValue()))).print("}");
+		}
+		if (newLine) {
+			this.writer.println();
+		}
+	}
+
+	private void writeArray(List<?> items, boolean newLine) {
+		if (items.isEmpty()) {
+			this.writer.print("[ ]");
+		}
+		else {
+			this.writer.println("[")
+					.indented(writeAll(items.iterator(), this::writeValue)).print("]");
+		}
+		if (newLine) {
+			this.writer.println();
+		}
+	}
+
+	private <T> Runnable writeAll(Iterator<T> it, Consumer<T> writer) {
+		return () -> {
+			while (it.hasNext()) {
+				writer.accept(it.next());
+				if (it.hasNext()) {
+					this.writer.println(",");
+				}
+				else {
+					this.writer.println();
+				}
+			}
+		};
+	}
+
+	private void writeAttribute(String name, Object value) {
+		this.writer.print(quote(name) + ": ");
+		writeValue(value);
+	}
+
+	@SuppressWarnings("unchecked")
+	private void writeValue(Object value) {
+		if (value instanceof Map<?, ?> map) {
+			writeObject((Map<String, Object>) map, false);
+		}
+		else if (value instanceof List<?> list) {
+			writeArray(list, false);
+		}
+		else if (value instanceof CharSequence string) {
+			this.writer.print(quote(escape(string)));
+		}
+		else if (value instanceof Boolean flag) {
+			this.writer.print(Boolean.toString(flag));
+		}
+		else {
+			throw new IllegalStateException("unsupported type: " + value.getClass());
+		}
+	}
+
+	private String quote(String name) {
+		return "\"" + name + "\"";
+	}
+
+	private static String escape(CharSequence input) {
+		StringBuilder builder = new StringBuilder();
+		input.chars().forEach(c -> {
+			switch (c) {
+				case '"':
+					builder.append("\\\"");
+					break;
+				case '\\':
+					builder.append("\\\\");
+					break;
+				case '/':
+					builder.append("\\/");
+					break;
+				case '\b':
+					builder.append("\\b");
+					break;
+				case '\f':
+					builder.append("\\f");
+					break;
+				case '\n':
+					builder.append("\\n");
+					break;
+				case '\r':
+					builder.append("\\r");
+					break;
+				case '\t':
+					builder.append("\\t");
+					break;
+				default:
+					if (c <= 0x1F) {
+						builder.append(String.format("\\u%04x", c));
+					}
+					else {
+						builder.append((char) c);
+					}
+					break;
+			}
+		});
+		return builder.toString();
+	}
+
+
+	static class IndentingWriter extends Writer {
+
+		private final Writer out;
+
+		private final String singleIndent;
+
+		private int level = 0;
+
+		private String currentIndent = "";
+
+		private boolean prependIndent = false;
+
+		IndentingWriter(Writer out, String singleIndent) {
+			this.out = out;
+			this.singleIndent = singleIndent;
+		}
+
+		/**
+		 * Write the specified text.
+		 * @param string the content to write
+		 */
+		public IndentingWriter print(String string) {
+			write(string.toCharArray(), 0, string.length());
+			return this;
+		}
+
+		/**
+		 * Write the specified text and append a new line.
+		 * @param string the content to write
+		 */
+		public IndentingWriter println(String string) {
+			write(string.toCharArray(), 0, string.length());
+			return println();
+		}
+
+		/**
+		 * Write a new line.
+		 */
+		public IndentingWriter println() {
+			String separator = System.lineSeparator();
+			try {
+				this.out.write(separator.toCharArray(), 0, separator.length());
+			}
+			catch (IOException ex) {
+				throw new IllegalStateException(ex);
+			}
+			this.prependIndent = true;
+			return this;
+		}
+
+		/**
+		 * Increase the indentation level and execute the {@link Runnable}. Decrease the
+		 * indentation level on completion.
+		 * @param runnable the code to execute withing an extra indentation level
+		 */
+		public IndentingWriter indented(Runnable runnable) {
+			indent();
+			runnable.run();
+			return outdent();
+		}
+
+		/**
+		 * Increase the indentation level.
+		 */
+		private IndentingWriter indent() {
+			this.level++;
+			return refreshIndent();
+		}
+
+		/**
+		 * Decrease the indentation level.
+		 */
+		private IndentingWriter outdent() {
+			this.level--;
+			return refreshIndent();
+		}
+
+		private IndentingWriter refreshIndent() {
+			this.currentIndent = this.singleIndent.repeat(Math.max(0, this.level));
+			return this;
+		}
+
+		@Override
+		public void write(char[] chars, int offset, int length) {
+			try {
+				if (this.prependIndent) {
+					this.out.write(this.currentIndent.toCharArray(), 0, this.currentIndent.length());
+					this.prependIndent = false;
+				}
+				this.out.write(chars, offset, length);
+			}
+			catch (IOException ex) {
+				throw new IllegalStateException(ex);
+			}
+		}
+
+		@Override
+		public void flush() throws IOException {
+			this.out.flush();
+		}
+
+		@Override
+		public void close() throws IOException {
+			this.out.close();
+		}
+
+	}
+
+}

spring-core/src/main/java/org/springframework/aot/nativex/FileNativeConfigurationGenerator.java

@@ -1,136 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-import java.io.File;
-import java.io.FileWriter;
-import java.io.IOException;
-import java.nio.file.Path;
-
-import org.springframework.aot.hint.JavaSerializationHints;
-import org.springframework.aot.hint.ProxyHints;
-import org.springframework.aot.hint.ReflectionHints;
-import org.springframework.aot.hint.ResourceHints;
-import org.springframework.aot.hint.RuntimeHints;
-import org.springframework.lang.Nullable;
-
-/**
- * Generate the GraalVM native configuration files from runtime hints.
- *
- * @author Sebastien Deleuze
- * @since 6.0
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
- */
-public class FileNativeConfigurationGenerator implements NativeConfigurationGenerator {
-
-	private final Path basePath;
-
-	private final String groupId;
-
-	private final String artifactId;
-
-	public FileNativeConfigurationGenerator(Path basePath) {
-		this(basePath, null, null);
-	}
-
-	public FileNativeConfigurationGenerator(Path basePath, @Nullable String groupId, @Nullable String artifactId) {
-		this.basePath = basePath;
-		if ((groupId == null && artifactId != null) || (groupId != null && artifactId == null)) {
-			throw new IllegalArgumentException("groupId and artifactId must be both null or both non-null");
-		}
-		this.groupId = groupId;
-		this.artifactId = artifactId;
-	}
-
-	@Override
-	public void generate(RuntimeHints hints) {
-		try {
-			if (hints.javaSerialization().types().findAny().isPresent()) {
-				generateFile(hints.javaSerialization());
-			}
-			if (hints.proxies().jdkProxies().findAny().isPresent()) {
-				generateFile(hints.proxies());
-			}
-			if (hints.reflection().typeHints().findAny().isPresent()) {
-				generateFile(hints.reflection());
-			}
-			if (hints.resources().resourcePatterns().findAny().isPresent() ||
-					hints.resources().resourceBundles().findAny().isPresent()) {
-				generateFile(hints.resources());
-			}
-		}
-		catch (IOException ex) {
-			throw new IllegalStateException("Unexpected I/O error while writing the native configuration", ex);
-		}
-	}
-
-	/**
-	 * Generate the Java serialization native configuration file.
-	 */
-	private void generateFile(JavaSerializationHints hints) throws IOException {
-		JavaSerializationHintsSerializer serializer = new JavaSerializationHintsSerializer();
-		File file = createIfNecessary("serialization-config.json");
-		FileWriter writer = new FileWriter(file);
-		writer.write(serializer.serialize(hints));
-		writer.close();
-	}
-
-	/**
-	 * Generate the proxy native configuration file.
-	 */
-	private void generateFile(ProxyHints hints) throws IOException {
-		ProxyHintsSerializer serializer = new ProxyHintsSerializer();
-		File file = createIfNecessary("proxy-config.json");
-		FileWriter writer = new FileWriter(file);
-		writer.write(serializer.serialize(hints));
-		writer.close();
-	}
-
-	/**
-	 * Generate the reflection native configuration file.
-	 */
-	private void generateFile(ReflectionHints hints) throws IOException {
-		ReflectionHintsSerializer serializer = new ReflectionHintsSerializer();
-		File file = createIfNecessary("reflect-config.json");
-		FileWriter writer = new FileWriter(file);
-		writer.write(serializer.serialize(hints));
-		writer.close();
-	}
-
-	/**
-	 * Generate the resource native configuration file.
-	 */
-	private void generateFile(ResourceHints hints) throws IOException {
-		ResourceHintsSerializer serializer = new ResourceHintsSerializer();
-		File file = createIfNecessary("resource-config.json");
-		FileWriter writer = new FileWriter(file);
-		writer.write(serializer.serialize(hints));
-		writer.close();
-	}
-
-	private File createIfNecessary(String filename) throws IOException {
-		Path outputDirectory = this.basePath.resolve("META-INF").resolve("native-image");
-		if (this.groupId != null && this.artifactId != null) {
-			outputDirectory = outputDirectory.resolve(this.groupId).resolve(this.artifactId);
-		}
-		outputDirectory.toFile().mkdirs();
-		File file = outputDirectory.resolve(filename).toFile();
-		file.createNewFile();
-		return file;
-	}
-
-}

spring-core/src/main/java/org/springframework/aot/nativex/FileNativeConfigurationWriter.java

@@ -0,0 +1,86 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.io.File;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.io.Writer;
+import java.nio.file.Path;
+import java.util.function.Consumer;
+
+import org.springframework.lang.Nullable;
+
+/**
+ * A {@link NativeConfigurationWriter} implementation that writes the
+ * configuration to disk.
+ *
+ * @author Sebastien Deleuze
+ * @author Stephane Nicoll
+ * @since 6.0
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
+ */
+public class FileNativeConfigurationWriter extends NativeConfigurationWriter {
+
+	private final Path basePath;
+
+	private final String groupId;
+
+	private final String artifactId;
+
+	public FileNativeConfigurationWriter(Path basePath) {
+		this(basePath, null, null);
+	}
+
+	public FileNativeConfigurationWriter(Path basePath, @Nullable String groupId, @Nullable String artifactId) {
+		this.basePath = basePath;
+		if ((groupId == null && artifactId != null) || (groupId != null && artifactId == null)) {
+			throw new IllegalArgumentException("groupId and artifactId must be both null or both non-null");
+		}
+		this.groupId = groupId;
+		this.artifactId = artifactId;
+	}
+
+	@Override
+	protected void writeTo(String fileName, Consumer<BasicJsonWriter> writer) {
+		try {
+			File file = createIfNecessary(fileName);
+			try (FileWriter out = new FileWriter(file)) {
+				writer.accept(createJsonWriter(out));
+			}
+		}
+		catch (IOException ex) {
+			throw new IllegalStateException("Failed to write native configuration for " + fileName, ex);
+		}
+	}
+
+	private File createIfNecessary(String filename) throws IOException {
+		Path outputDirectory = this.basePath.resolve("META-INF").resolve("native-image");
+		if (this.groupId != null && this.artifactId != null) {
+			outputDirectory = outputDirectory.resolve(this.groupId).resolve(this.artifactId);
+		}
+		outputDirectory.toFile().mkdirs();
+		File file = outputDirectory.resolve(filename).toFile();
+		file.createNewFile();
+		return file;
+	}
+
+	private BasicJsonWriter createJsonWriter(Writer out) {
+		return new BasicJsonWriter(out);
+	}
+
+}

spring-core/src/main/java/org/springframework/aot/nativex/JavaSerializationHintsWriter.java

@@ -16,35 +16,34 @@
 
 package org.springframework.aot.nativex;
 
-import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
 
 import org.springframework.aot.hint.JavaSerializationHints;
 import org.springframework.aot.hint.TypeReference;
 
 /**
- * Serialize a {@link JavaSerializationHints} to the JSON file expected by GraalVM {@code native-image} compiler,
- * typically named {@code serialization-config.json}.
+ * Write a {@link JavaSerializationHints} to the JSON output expected by the
+ * GraalVM {@code native-image} compiler, typically named
+ * {@code serialization-config.json}.
  *
  * @author Sebastien Deleuze
+ * @author Stephane Nicoll
  * @since 6.0
  * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
  */
-class JavaSerializationHintsSerializer {
-
-	public String serialize(JavaSerializationHints hints) {
-		StringBuilder builder = new StringBuilder();
-		builder.append("[\n");
-		Iterator<TypeReference> typeIterator = hints.types().iterator();
-		while (typeIterator.hasNext()) {
-			TypeReference type = typeIterator.next();
-			String name = JsonUtils.escape(type.getCanonicalName());
-			builder.append("{ \"name\": \"").append(name).append("\" }");
-			if (typeIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("\n]\n");
-		return builder.toString();
+class JavaSerializationHintsWriter {
+
+	public static final JavaSerializationHintsWriter INSTANCE = new JavaSerializationHintsWriter();
+
+	public void write(BasicJsonWriter writer, JavaSerializationHints hints) {
+		writer.writeArray(hints.types().map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(TypeReference typeReference) {
+		LinkedHashMap<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("name", typeReference.getCanonicalName());
+		return attributes;
 	}
 
 }

spring-core/src/main/java/org/springframework/aot/nativex/JsonUtils.java

@@ -1,69 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-/**
- * Utility class for JSON.
- *
- * @author Sebastien Deleuze
- */
-abstract class JsonUtils {
-
-	/**
-	 * Escape a JSON String.
-	 */
-	static String escape(String input) {
-		StringBuilder builder = new StringBuilder();
-		input.chars().forEach(c -> {
-			switch (c) {
-				case '"':
-					builder.append("\\\"");
-					break;
-				case '\\':
-					builder.append("\\\\");
-					break;
-				case '/':
-					builder.append("\\/");
-					break;
-				case '\b':
-					builder.append("\\b");
-					break;
-				case '\f':
-					builder.append("\\f");
-					break;
-				case '\n':
-					builder.append("\\n");
-					break;
-				case '\r':
-					builder.append("\\r");
-					break;
-				case '\t':
-					builder.append("\\t");
-					break;
-				default:
-					if (c <= 0x1F) {
-						builder.append(String.format("\\u%04x", c));
-					}
-					else {
-						builder.append((char) c);
-					}
-					break;
-			}
-		});
-		return builder.toString();
-	}
-}

spring-core/src/main/java/org/springframework/aot/nativex/NativeConfigurationGenerator.java

@@ -1,36 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-import org.springframework.aot.hint.RuntimeHints;
-
-/**
- * Generate GraalVM native configuration.
- *
- * @author Sebastien Deleuze
- * @since 6.0
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
- */
-public interface NativeConfigurationGenerator {
-
-	/**
-	 * Generate the GraalVM native configuration from the provided hints.
-	 * @param hints the hints to serialize
-	 */
-	void generate(RuntimeHints hints);
-
-}

spring-core/src/main/java/org/springframework/aot/nativex/NativeConfigurationWriter.java

@@ -0,0 +1,85 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.util.function.Consumer;
+
+import org.springframework.aot.hint.JavaSerializationHints;
+import org.springframework.aot.hint.ProxyHints;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.aot.hint.ResourceHints;
+import org.springframework.aot.hint.RuntimeHints;
+
+/**
+ * Write {@link RuntimeHints} as GraalVM native configuration.
+ *
+ * @author Sebastien Deleuze
+ * @author Stephane Nicoll
+ * @since 6.0
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
+ */
+public abstract class NativeConfigurationWriter {
+
+	/**
+	 * Write the GraalVM native configuration from the provided hints.
+	 * @param hints the hints to handle
+	 */
+	public void write(RuntimeHints hints) {
+		if (hints.javaSerialization().types().findAny().isPresent()) {
+			writeJavaSerializationHints(hints.javaSerialization());
+		}
+		if (hints.proxies().jdkProxies().findAny().isPresent()) {
+			writeProxyHints(hints.proxies());
+		}
+		if (hints.reflection().typeHints().findAny().isPresent()) {
+			writeReflectionHints(hints.reflection());
+		}
+		if (hints.resources().resourcePatterns().findAny().isPresent() ||
+				hints.resources().resourceBundles().findAny().isPresent()) {
+			writeResourceHints(hints.resources());
+		}
+	}
+
+	/**
+	 * Write the specified GraalVM native configuration file, using the
+	 * provided {@link BasicJsonWriter}.
+	 * @param fileName the name of the file
+	 * @param writer a consumer for the writer to use
+	 */
+	protected abstract void writeTo(String fileName, Consumer<BasicJsonWriter> writer);
+
+	private void writeJavaSerializationHints(JavaSerializationHints hints) {
+		writeTo("serialization-config.json", writer ->
+				JavaSerializationHintsWriter.INSTANCE.write(writer, hints));
+	}
+
+	private void writeProxyHints(ProxyHints hints) {
+		writeTo("proxy-config.json", writer ->
+				ProxyHintsWriter.INSTANCE.write(writer, hints));
+	}
+
+	private void writeReflectionHints(ReflectionHints hints) {
+		writeTo("reflect-config.json", writer ->
+				ReflectionHintsWriter.INSTANCE.write(writer, hints));
+	}
+
+	private void writeResourceHints(ResourceHints hints) {
+		writeTo("resource-config.json", writer ->
+				ResourceHintsWriter.INSTANCE.write(writer, hints));
+	}
+
+}

spring-core/src/main/java/org/springframework/aot/nativex/ProxyHintsWriter.java

@@ -16,45 +16,37 @@
 
 package org.springframework.aot.nativex;
 
-import java.util.Iterator;
+import java.util.LinkedHashMap;
+import java.util.Map;
 
 import org.springframework.aot.hint.JdkProxyHint;
 import org.springframework.aot.hint.ProxyHints;
 import org.springframework.aot.hint.TypeReference;
 
 /**
- * Serialize {@link JdkProxyHint}s contained in a {@link ProxyHints} to the JSON file expected by GraalVM
- * {@code native-image} compiler, typically named {@code proxy-config.json}.
+ * Write {@link JdkProxyHint}s contained in a {@link ProxyHints} to the JSON
+ * output expected by the GraalVM {@code native-image} compiler, typically named
+ * {@code proxy-config.json}.
  *
  * @author Sebastien Deleuze
+ * @author Stephane Nicoll
  * @since 6.0
  * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/DynamicProxy/">Dynamic Proxy in Native Image</a>
  * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
  */
-class ProxyHintsSerializer {
-
-	public String serialize(ProxyHints hints) {
-		StringBuilder builder = new StringBuilder();
-		builder.append("[\n");
-		Iterator<JdkProxyHint> hintIterator = hints.jdkProxies().iterator();
-		while (hintIterator.hasNext()) {
-			builder.append("{ \"interfaces\": [ ");
-			JdkProxyHint hint = hintIterator.next();
-			Iterator<TypeReference> interfaceIterator = hint.getProxiedInterfaces().iterator();
-			while (interfaceIterator.hasNext()) {
-				String name = JsonUtils.escape(interfaceIterator.next().getCanonicalName());
-				builder.append("\"").append(name).append("\"");
-				if (interfaceIterator.hasNext()) {
-					builder.append(", ");
-				}
-			}
-			builder.append(" ] }");
-			if (hintIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("\n]\n");
-		return builder.toString();
+class ProxyHintsWriter {
+
+	public static final ProxyHintsWriter INSTANCE = new ProxyHintsWriter();
+
+	public void write(BasicJsonWriter writer, ProxyHints hints) {
+		writer.writeArray(hints.jdkProxies().map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(JdkProxyHint hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("interfaces", hint.getProxiedInterfaces().stream()
+				.map(TypeReference::getCanonicalName).toList());
+		return attributes;
 	}
 
 }

spring-core/src/main/java/org/springframework/aot/nativex/ReflectionHintsSerializer.java

@@ -1,156 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-import java.util.Iterator;
-import java.util.List;
-import java.util.stream.Stream;
-
-import org.springframework.aot.hint.ExecutableHint;
-import org.springframework.aot.hint.ExecutableMode;
-import org.springframework.aot.hint.FieldHint;
-import org.springframework.aot.hint.MemberCategory;
-import org.springframework.aot.hint.ReflectionHints;
-import org.springframework.aot.hint.TypeHint;
-import org.springframework.aot.hint.TypeReference;
-
-/**
- * Serialize {@link ReflectionHints} to the JSON file expected by GraalVM {@code native-image} compiler,
- * typically named {@code reflect-config.json}.
- *
- * @author Sebastien Deleuze
- * @since 6.0
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/Reflection/">Reflection Use in Native Images</a>
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
- */
-@SuppressWarnings("serial")
-class ReflectionHintsSerializer {
-
-	public String serialize(ReflectionHints hints) {
-		StringBuilder builder = new StringBuilder();
-		builder.append("[\n");
-		Iterator<TypeHint> hintIterator = hints.typeHints().iterator();
-		while (hintIterator.hasNext()) {
-			TypeHint hint = hintIterator.next();
-			String name = JsonUtils.escape(hint.getType().getCanonicalName());
-			builder.append("{\n\"name\": \"").append(name).append("\"");
-			serializeCondition(hint, builder);
-			serializeMembers(hint, builder);
-			serializeFields(hint, builder);
-			serializeExecutables(hint, builder);
-			builder.append(" }");
-			if (hintIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("\n]");
-		return builder.toString();
-	}
-
-	private void serializeCondition(TypeHint hint, StringBuilder builder) {
-		if (hint.getReachableType() != null) {
-			String name = JsonUtils.escape(hint.getReachableType().getCanonicalName());
-			builder.append(",\n\"condition\": { \"typeReachable\": \"").append(name).append("\" }");
-		}
-	}
-
-	private void serializeFields(TypeHint hint, StringBuilder builder) {
-		Iterator<FieldHint> fieldIterator = hint.fields().iterator();
-		if (fieldIterator.hasNext()) {
-			builder.append(",\n\"fields\": [\n");
-			while (fieldIterator.hasNext()) {
-				FieldHint fieldHint = fieldIterator.next();
-				String name = JsonUtils.escape(fieldHint.getName());
-				builder.append("{ \"name\": \"").append(name).append("\"");
-				if (fieldHint.isAllowWrite()) {
-					builder.append(", \"allowWrite\": ").append(fieldHint.isAllowWrite());
-				}
-				if (fieldHint.isAllowUnsafeAccess()) {
-					builder.append(", \"allowUnsafeAccess\": ").append(fieldHint.isAllowUnsafeAccess());
-				}
-				builder.append(" }");
-				if (fieldIterator.hasNext()) {
-					builder.append(",\n");
-				}
-			}
-			builder.append("\n]");
-		}
-	}
-
-	private void serializeExecutables(TypeHint hint, StringBuilder builder) {
-		List<ExecutableHint> executables = Stream.concat(hint.constructors(), hint.methods()).toList();
-		Iterator<ExecutableHint> methodIterator = executables.stream().filter(h -> h.getModes().contains(ExecutableMode.INVOKE) || h.getModes().isEmpty()).iterator();
-		Iterator<ExecutableHint> queriedMethodIterator = executables.stream().filter(h -> h.getModes().contains(ExecutableMode.INTROSPECT)).iterator();
-		if (methodIterator.hasNext()) {
-			builder.append(",\n");
-			serializeMethods("methods", methodIterator, builder);
-		}
-		if (queriedMethodIterator.hasNext()) {
-			builder.append(",\n");
-			serializeMethods("queriedMethods", queriedMethodIterator, builder);
-		}
-	}
-
-	private void serializeMethods(String fieldName, Iterator<ExecutableHint> methodIterator, StringBuilder builder) {
-		builder.append("\"").append(JsonUtils.escape(fieldName)).append("\": [\n");
-		while (methodIterator.hasNext()) {
-			ExecutableHint hint = methodIterator.next();
-			String name = JsonUtils.escape(hint.getName());
-			builder.append("{\n\"name\": \"").append(name).append("\", ").append("\"parameterTypes\": [ ");
-			Iterator<TypeReference> parameterIterator =  hint.getParameterTypes().iterator();
-			while (parameterIterator.hasNext()) {
-				String parameterName = JsonUtils.escape(parameterIterator.next().getCanonicalName());
-				builder.append("\"").append(parameterName).append("\"");
-				if (parameterIterator.hasNext()) {
-					builder.append(", ");
-				}
-			}
-			builder.append(" ] }\n");
-			if (methodIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("]\n");
-	}
-
-	private void serializeMembers(TypeHint hint, StringBuilder builder) {
-		Iterator<MemberCategory> categoryIterator = hint.getMemberCategories().iterator();
-		if (categoryIterator.hasNext()) {
-			builder.append(",\n");
-			while (categoryIterator.hasNext()) {
-				switch (categoryIterator.next()) {
-					case PUBLIC_FIELDS -> builder.append("\"allPublicFields\": true");
-					case DECLARED_FIELDS -> builder.append("\"allDeclaredFields\": true");
-					case INTROSPECT_PUBLIC_CONSTRUCTORS -> builder.append("\"queryAllPublicConstructors\": true");
-					case INTROSPECT_DECLARED_CONSTRUCTORS -> builder.append("\"queryAllDeclaredConstructors\": true");
-					case INVOKE_PUBLIC_CONSTRUCTORS -> builder.append("\"allPublicConstructors\": true");
-					case INVOKE_DECLARED_CONSTRUCTORS -> builder.append("\"allDeclaredConstructors\": true");
-					case INTROSPECT_PUBLIC_METHODS -> builder.append("\"queryAllPublicMethods\": true");
-					case INTROSPECT_DECLARED_METHODS -> builder.append("\"queryAllDeclaredMethods\": true");
-					case INVOKE_PUBLIC_METHODS -> builder.append("\"allPublicMethods\": true");
-					case INVOKE_DECLARED_METHODS -> builder.append("\"allDeclaredMethods\": true");
-					case PUBLIC_CLASSES -> builder.append("\"allPublicClasses\": true");
-					case DECLARED_CLASSES -> builder.append("\"allDeclaredClasses\": true");
-				}
-				if (categoryIterator.hasNext()) {
-					builder.append(",\n");
-				}
-			}
-		}
-	}
-
-}

spring-core/src/main/java/org/springframework/aot/nativex/ReflectionHintsWriter.java

@@ -0,0 +1,129 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.stream.Stream;
+
+import org.springframework.aot.hint.ExecutableHint;
+import org.springframework.aot.hint.ExecutableMode;
+import org.springframework.aot.hint.FieldHint;
+import org.springframework.aot.hint.MemberCategory;
+import org.springframework.aot.hint.ReflectionHints;
+import org.springframework.aot.hint.TypeHint;
+import org.springframework.aot.hint.TypeReference;
+import org.springframework.lang.Nullable;
+
+/**
+ * Write {@link ReflectionHints} to the JSON output expected by the GraalVM
+ * {@code native-image} compiler, typically named {@code reflect-config.json}.
+ *
+ * @author Sebastien Deleuze
+ * @author Stephane Nicoll
+ * @since 6.0
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/Reflection/">Reflection Use in Native Images</a>
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
+ */
+class ReflectionHintsWriter {
+
+	public static final ReflectionHintsWriter INSTANCE = new ReflectionHintsWriter();
+
+	public void write(BasicJsonWriter writer, ReflectionHints hints) {
+		writer.writeArray(hints.typeHints().map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(TypeHint hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("name", hint.getType().getCanonicalName());
+		handleCondition(attributes, hint);
+		handleCategories(attributes, hint.getMemberCategories());
+		handleFields(attributes, hint.fields());
+		handleExecutables(attributes, Stream.concat(hint.constructors(), hint.methods()).toList());
+		return attributes;
+	}
+
+	private void handleCondition(Map<String, Object> attributes, TypeHint hint) {
+		if (hint.getReachableType() != null) {
+			Map<String, Object> conditionAttributes = new LinkedHashMap<>();
+			conditionAttributes.put("typeReachable", hint.getReachableType().getCanonicalName());
+			attributes.put("condition", conditionAttributes);
+		}
+	}
+
+	private void handleFields(Map<String, Object> attributes, Stream<FieldHint> fields) {
+		addIfNotEmpty(attributes, "fields", fields.map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(FieldHint hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("name", hint.getName());
+		if (hint.isAllowWrite()) {
+			attributes.put("allowWrite", hint.isAllowWrite());
+		}
+		if (hint.isAllowUnsafeAccess()) {
+			attributes.put("allowUnsafeAccess", hint.isAllowUnsafeAccess());
+		}
+		return attributes;
+	}
+
+	private void handleExecutables(Map<String, Object> attributes, List<ExecutableHint> hints) {
+		addIfNotEmpty(attributes, "methods", hints.stream()
+				.filter(h -> h.getModes().contains(ExecutableMode.INVOKE) || h.getModes().isEmpty())
+				.map(this::toAttributes).toList());
+		addIfNotEmpty(attributes, "queriedMethods", hints.stream()
+				.filter(h -> h.getModes().contains(ExecutableMode.INTROSPECT))
+				.map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(ExecutableHint hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("name", hint.getName());
+		attributes.put("parameterTypes", hint.getParameterTypes().stream().map(TypeReference::getCanonicalName).toList());
+		return attributes;
+	}
+
+	private void handleCategories(Map<String, Object> attributes, Set<MemberCategory> categories) {
+		categories.forEach(category -> {
+					switch (category) {
+						case PUBLIC_FIELDS -> attributes.put("allPublicFields", true);
+						case DECLARED_FIELDS -> attributes.put("allDeclaredFields", true);
+						case INTROSPECT_PUBLIC_CONSTRUCTORS -> attributes.put("queryAllPublicConstructors", true);
+						case INTROSPECT_DECLARED_CONSTRUCTORS -> attributes.put("queryAllDeclaredConstructors", true);
+						case INVOKE_PUBLIC_CONSTRUCTORS -> attributes.put("allPublicConstructors", true);
+						case INVOKE_DECLARED_CONSTRUCTORS -> attributes.put("allDeclaredConstructors", true);
+						case INTROSPECT_PUBLIC_METHODS -> attributes.put("queryAllPublicMethods", true);
+						case INTROSPECT_DECLARED_METHODS -> attributes.put("queryAllDeclaredMethods", true);
+						case INVOKE_PUBLIC_METHODS -> attributes.put("allPublicMethods", true);
+						case INVOKE_DECLARED_METHODS -> attributes.put("allDeclaredMethods", true);
+						case PUBLIC_CLASSES -> attributes.put("allPublicClasses", true);
+						case DECLARED_CLASSES -> attributes.put("allDeclaredClasses", true);
+					}
+				}
+		);
+	}
+
+	private void addIfNotEmpty(Map<String, Object> attributes, String name, @Nullable Object value) {
+		if (value != null && (value instanceof Collection<?> collection && !collection.isEmpty())) {
+			attributes.put(name, value);
+		}
+	}
+
+}

spring-core/src/main/java/org/springframework/aot/nativex/ResourceHintsSerializer.java

@@ -1,107 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-import java.util.Arrays;
-import java.util.Iterator;
-import java.util.regex.Pattern;
-import java.util.stream.Collectors;
-
-import org.springframework.aot.hint.ResourceBundleHint;
-import org.springframework.aot.hint.ResourceHints;
-import org.springframework.aot.hint.ResourcePatternHint;
-
-/**
- * Serialize a {@link ResourceHints} to the JSON file expected by GraalVM {@code native-image} compiler,
- * typically named {@code resource-config.json}.
- *
- * @author Sebastien Deleuze
- * @since 6.0
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/Resources/">Accessing Resources in Native Images</a>
- * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
- */
-class ResourceHintsSerializer {
-
-	public String serialize(ResourceHints hints) {
-		StringBuilder builder = new StringBuilder();
-		builder.append("{\n\"resources\" : {\n");
-		serializeInclude(hints, builder);
-		serializeExclude(hints, builder);
-		builder.append("},\n");
-		serializeBundles(hints, builder);
-		builder.append("}\n");
-		return builder.toString();
-	}
-
-	private void serializeInclude(ResourceHints hints, StringBuilder builder) {
-		builder.append("\"includes\" : [\n");
-		Iterator<ResourcePatternHint> patternIterator = hints.resourcePatterns().iterator();
-		while (patternIterator.hasNext()) {
-			ResourcePatternHint hint = patternIterator.next();
-			Iterator<String> includeIterator = hint.getIncludes().iterator();
-			while (includeIterator.hasNext()) {
-				String pattern = JsonUtils.escape(patternToRegexp(includeIterator.next()));
-				builder.append("{ \"pattern\": \"").append(pattern).append("\" }");
-				if (includeIterator.hasNext()) {
-					builder.append(", ");
-				}
-			}
-			if (patternIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("\n],\n");
-	}
-
-	private void serializeExclude(ResourceHints hints, StringBuilder builder) {
-		builder.append("\"excludes\" : [\n");
-		Iterator<ResourcePatternHint> patternIterator = hints.resourcePatterns().iterator();
-		while (patternIterator.hasNext()) {
-			ResourcePatternHint hint = patternIterator.next();
-			Iterator<String> excludeIterator = hint.getExcludes().iterator();
-			while (excludeIterator.hasNext()) {
-				String pattern = JsonUtils.escape(patternToRegexp(excludeIterator.next()));
-				builder.append("{ \"pattern\": \"").append(pattern).append("\" }");
-				if (excludeIterator.hasNext()) {
-					builder.append(", ");
-				}
-			}
-			if (patternIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("\n]\n");
-	}
-
-	private void serializeBundles(ResourceHints hints, StringBuilder builder) {
-		builder.append("\"bundles\" : [\n");
-		Iterator<ResourceBundleHint> bundleIterator = hints.resourceBundles().iterator();
-		while (bundleIterator.hasNext()) {
-			String baseName = JsonUtils.escape(bundleIterator.next().getBaseName());
-			builder.append("{ \"name\": \"").append(baseName).append("\" }");
-			if (bundleIterator.hasNext()) {
-				builder.append(",\n");
-			}
-		}
-		builder.append("]\n");
-	}
-
-	private String patternToRegexp(String pattern) {
-		return Arrays.stream(pattern.split("\\*")).map(Pattern::quote).collect(Collectors.joining(".*"));
-	}
-
-}

spring-core/src/main/java/org/springframework/aot/nativex/ResourceHintsWriter.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.util.Arrays;
+import java.util.Collection;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.regex.Pattern;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+import org.springframework.aot.hint.ResourceBundleHint;
+import org.springframework.aot.hint.ResourceHints;
+import org.springframework.aot.hint.ResourcePatternHint;
+import org.springframework.lang.Nullable;
+
+/**
+ * Write a {@link ResourceHints} to the JSON output expected by the GraalVM
+ * {@code native-image} compiler, typically named {@code resource-config.json}.
+ *
+ * @author Sebastien Deleuze
+ * @author Stephane Nicoll
+ * @since 6.0
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/Resources/">Accessing Resources in Native Images</a>
+ * @see <a href="https://www.graalvm.org/22.0/reference-manual/native-image/BuildConfiguration/">Native Image Build Configuration</a>
+ */
+class ResourceHintsWriter {
+
+	public static final ResourceHintsWriter INSTANCE = new ResourceHintsWriter();
+
+	public void write(BasicJsonWriter writer, ResourceHints hints) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		addIfNotEmpty(attributes, "resources", toAttributes(hints));
+		handleResourceBundles(attributes, hints.resourceBundles());
+		writer.writeObject(attributes);
+	}
+
+	private Map<String, Object> toAttributes(ResourceHints hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		addIfNotEmpty(attributes, "includes", hint.resourcePatterns().map(ResourcePatternHint::getIncludes)
+				.flatMap(List::stream).distinct().map(this::toAttributes).toList());
+		addIfNotEmpty(attributes, "excludes", hint.resourcePatterns().map(ResourcePatternHint::getExcludes)
+				.flatMap(List::stream).distinct().map(this::toAttributes).toList());
+		return attributes;
+	}
+
+	private void handleResourceBundles(Map<String, Object> attributes, Stream<ResourceBundleHint> ressourceBundles) {
+		addIfNotEmpty(attributes, "bundles", ressourceBundles.map(this::toAttributes).toList());
+	}
+
+	private Map<String, Object> toAttributes(ResourceBundleHint hint) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("name", hint.getBaseName());
+		return attributes;
+	}
+
+	private Map<String, Object> toAttributes(String pattern) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("pattern", patternToRegexp(pattern));
+		return attributes;
+	}
+
+	private String patternToRegexp(String pattern) {
+		return Arrays.stream(pattern.split("\\*")).map(Pattern::quote).collect(Collectors.joining(".*"));
+	}
+
+	private void addIfNotEmpty(Map<String, Object> attributes, String name, @Nullable Object value) {
+		if (value instanceof Collection<?> collection) {
+			if (!collection.isEmpty()) {
+				attributes.put(name, value);
+			}
+		}
+		else if (value instanceof Map<?, ?> map) {
+			if (!map.isEmpty()) {
+				attributes.put(name, value);
+			}
+		}
+		else if (value != null) {
+			attributes.put(name, value);
+		}
+	}
+
+}

spring-core/src/test/java/org/springframework/aot/nativex/BasicJsonWriterTests.java

@@ -0,0 +1,190 @@
+/*
+ * Copyright 2002-2022 the original author or authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.springframework.aot.nativex;
+
+import java.io.StringWriter;
+import java.util.Collections;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link BasicJsonWriter}.
+ *
+ * @author Stephane Nicoll
+ */
+class BasicJsonWriterTests {
+
+	private final StringWriter out = new StringWriter();
+
+	private final BasicJsonWriter json = new BasicJsonWriter(out, "\t");
+
+	@Test
+	void writeObject() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		attributes.put("another", true);
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"another": true
+				}
+				""");
+	}
+
+	@Test
+	void writeObjectWitNestedObject() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		attributes.put("nested", orderedMap("enabled", false));
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"nested": {
+						"enabled": false
+					}
+				}
+				""");
+	}
+
+	@Test
+	void writeObjectWitNestedArrayOfString() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		attributes.put("nested", List.of("test", "value", "another"));
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"nested": [
+						"test",
+						"value",
+						"another"
+					]
+				}
+				""");
+	}
+
+	@Test
+	void writeObjectWitNestedArrayOfObject() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		LinkedHashMap<String, Object> secondNested = orderedMap("name", "second");
+		secondNested.put("enabled", false);
+		attributes.put("nested", List.of(orderedMap("name", "first"), secondNested, orderedMap("name", "third")));
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"nested": [
+						{
+							"name": "first"
+						},
+						{
+							"name": "second",
+							"enabled": false
+						},
+						{
+							"name": "third"
+						}
+					]
+				}
+				""");
+	}
+
+	@Test
+	void writeObjectWithNestedEmptyArray() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		attributes.put("nested", Collections.emptyList());
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"nested": [ ]
+				}
+				""");
+	}
+
+	@Test
+	void writeObjectWithNestedEmptyObject() {
+		Map<String, Object> attributes = orderedMap("test", "value");
+		attributes.put("nested", Collections.emptyMap());
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).isEqualTo("""
+				{
+					"test": "value",
+					"nested": { }
+				}
+				""");
+	}
+
+	@Test
+	void writeWithEscapeDoubleQuote() {
+		assertEscapedValue("foo\"bar", "foo\\\"bar");
+	}
+
+	@Test
+	void writeWithEscapeBackslash() {
+		assertEscapedValue("foo\"bar", "foo\\\"bar");
+	}
+
+	@Test
+	void writeWithEscapeBackspace() {
+		assertEscapedValue("foo\bbar", "foo\\bbar");
+	}
+
+	@Test
+	void writeWithEscapeFormFeed() {
+		assertEscapedValue("foo\fbar", "foo\\fbar");
+	}
+
+	@Test
+	void writeWithEscapeNewline() {
+		assertEscapedValue("foo\nbar", "foo\\nbar");
+	}
+
+	@Test
+	void writeWithEscapeCarriageReturn() {
+		assertEscapedValue("foo\rbar", "foo\\rbar");
+	}
+
+	@Test
+	void writeWithEscapeTab() {
+		assertEscapedValue("foo\tbar", "foo\\tbar");
+	}
+
+	@Test
+	void writeWithEscapeUnicode() {
+		assertEscapedValue("foo\u001Fbar", "foo\\u001fbar");
+	}
+
+	void assertEscapedValue(String value, String expectedEscapedValue) {
+		Map<String, Object> attributes = new LinkedHashMap<>();
+		attributes.put("test", value);
+		this.json.writeObject(attributes);
+		assertThat(out.toString()).contains("\"test\": \"" + expectedEscapedValue + "\"");
+	}
+
+	private static LinkedHashMap<String, Object> orderedMap(String key, Object value) {
+		LinkedHashMap<String, Object> map = new LinkedHashMap<>();
+		map.put(key, value);
+		return map;
+	}
+
+}

spring-core/src/test/java/org/springframework/aot/nativex/FileNativeConfigurationWriterTests.java

@@ -45,11 +45,11 @@ import org.springframework.util.MimeType;
 import static org.assertj.core.api.Assertions.assertThat;
 
 /**
- * Tests for {@link FileNativeConfigurationGenerator}.
+ * Tests for {@link FileNativeConfigurationWriter}.
  *
  * @author Sebastien Deleuze
  */
-public class FileNativeConfigurationGeneratorTests {
+public class FileNativeConfigurationWriterTests {
 
 	@TempDir
 	static Path tempDir;
@@ -57,44 +57,44 @@ public class FileNativeConfigurationGeneratorTests {
 	@Test
 	void emptyConfig() {
 		Path empty = tempDir.resolve("empty");
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(empty);
-		generator.generate(new RuntimeHints());
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(empty);
+		generator.write(new RuntimeHints());
 		assertThat(empty.toFile().listFiles()).isNull();
 	}
 
 	@Test
 	void serializationConfig() throws IOException, JSONException {
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(tempDir);
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(tempDir);
 		RuntimeHints hints = new RuntimeHints();
 		JavaSerializationHints serializationHints = hints.javaSerialization();
 		serializationHints.registerType(Integer.class);
 		serializationHints.registerType(Long.class);
-		generator.generate(hints);
+		generator.write(hints);
 		assertEquals("""
 				[
-					{ "name" : "java.lang.Integer" },
-					{ "name" : "java.lang.Long" }
+					{ "name": "java.lang.Integer" },
+					{ "name": "java.lang.Long" }
 				]""", "serialization-config.json");
 	}
 
 	@Test
 	void proxyConfig() throws IOException, JSONException {
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(tempDir);
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(tempDir);
 		RuntimeHints hints = new RuntimeHints();
 		ProxyHints proxyHints = hints.proxies();
 		proxyHints.registerJdkProxy(Function.class);
 		proxyHints.registerJdkProxy(Function.class, Consumer.class);
-		generator.generate(hints);
+		generator.write(hints);
 		assertEquals("""
 				[
-					{ "interfaces" : [ "java.util.function.Function" ] },
-					{ "interfaces" : [ "java.util.function.Function", "java.util.function.Consumer" ] }
+					{ "interfaces": [ "java.util.function.Function" ] },
+					{ "interfaces": [ "java.util.function.Function", "java.util.function.Consumer" ] }
 				]""", "proxy-config.json");
 	}
 
 	@Test
 	void reflectionConfig() throws IOException, JSONException {
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(tempDir);
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(tempDir);
 		RuntimeHints hints = new RuntimeHints();
 		ReflectionHints reflectionHints = hints.reflection();
 		reflectionHints.registerType(StringDecoder.class, builder -> {
@@ -117,34 +117,34 @@ public class FileNativeConfigurationGeneratorTests {
 					.withMethod("getDefaultCharset", Collections.emptyList(), constructorHint ->
 							constructorHint.withMode(ExecutableMode.INTROSPECT));
 		});
-		generator.generate(hints);
+		generator.write(hints);
 		assertEquals("""
 				[
 					{
-						"name" : "org.springframework.core.codec.StringDecoder",
-						"condition" : { "typeReachable" : "java.lang.String" },
-						"allPublicFields" : true,
-						"allDeclaredFields" : true,
-						"queryAllPublicConstructors" : true,
-						"queryAllDeclaredConstructors" : true,
-						"allPublicConstructors" : true,
-						"allDeclaredConstructors" : true,
-						"queryAllPublicMethods" : true,
-						"queryAllDeclaredMethods" : true,
-						"allPublicMethods" : true,
-						"allDeclaredMethods" : true,
-						"allPublicClasses" : true,
-						"allDeclaredClasses" : true,
-						"fields" : [
-							{ "name" : "DEFAULT_CHARSET" },
-							{ "name" : "defaultCharset", "allowWrite" = true, "allowUnsafeAccess" = true }
+						"name": "org.springframework.core.codec.StringDecoder",
+						"condition": { "typeReachable": "java.lang.String" },
+						"allPublicFields": true,
+						"allDeclaredFields": true,
+						"queryAllPublicConstructors": true,
+						"queryAllDeclaredConstructors": true,
+						"allPublicConstructors": true,
+						"allDeclaredConstructors": true,
+						"queryAllPublicMethods": true,
+						"queryAllDeclaredMethods": true,
+						"allPublicMethods": true,
+						"allDeclaredMethods": true,
+						"allPublicClasses": true,
+						"allDeclaredClasses": true,
+						"fields": [
+							{ "name": "DEFAULT_CHARSET" },
+							{ "name": "defaultCharset", "allowWrite": true, "allowUnsafeAccess": true }
 						],
-						"methods" : [
-							{ "name" : "setDefaultCharset", "parameterTypes": [ "java.nio.charset.Charset" ] }
+						"methods": [
+							{ "name": "setDefaultCharset", "parameterTypes": [ "java.nio.charset.Charset" ] }
 						],
-						"queriedMethods" :  [
-							{ "name" : "<init>", "parameterTypes": [ "java.util.List", "boolean", "org.springframework.util.MimeType" ] },
-							{ "name" : "getDefaultCharset" }
+						"queriedMethods":  [
+							{ "name": "<init>", "parameterTypes": [ "java.util.List", "boolean", "org.springframework.util.MimeType" ] },
+							{ "name": "getDefaultCharset", "parameterTypes": [ ] }
 						]
 					}
 				]""", "reflect-config.json");
@@ -152,18 +152,18 @@ public class FileNativeConfigurationGeneratorTests {
 
 	@Test
 	void resourceConfig() throws IOException, JSONException {
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(tempDir);
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(tempDir);
 		RuntimeHints hints = new RuntimeHints();
 		ResourceHints resourceHints = hints.resources();
 		resourceHints.registerPattern("com/example/test.properties");
 		resourceHints.registerPattern("com/example/another.properties");
-		generator.generate(hints);
+		generator.write(hints);
 		assertEquals("""
 				{
 					"resources": {
-						"includes" : [
-							{"pattern" : "\\\\Qcom/example/test.properties\\\\E"},
-							{"pattern" : "\\\\Qcom/example/another.properties\\\\E"}
+						"includes": [
+							{"pattern": "\\\\Qcom/example/test.properties\\\\E"},
+							{"pattern": "\\\\Qcom/example/another.properties\\\\E"}
 						]
 					}
 				}""", "resource-config.json");
@@ -174,11 +174,11 @@ public class FileNativeConfigurationGeneratorTests {
 		String groupId = "foo.bar";
 		String artifactId = "baz";
 		String filename = "resource-config.json";
-		FileNativeConfigurationGenerator generator = new FileNativeConfigurationGenerator(tempDir, groupId, artifactId);
+		FileNativeConfigurationWriter generator = new FileNativeConfigurationWriter(tempDir, groupId, artifactId);
 		RuntimeHints hints = new RuntimeHints();
 		ResourceHints resourceHints = hints.resources();
 		resourceHints.registerPattern("com/example/test.properties");
-		generator.generate(hints);
+		generator.write(hints);
 		Path jsonFile = tempDir.resolve("META-INF").resolve("native-image").resolve(groupId).resolve(artifactId).resolve(filename);
 		assertThat(jsonFile.toFile().exists()).isTrue();
 	}
@@ -186,7 +186,7 @@ public class FileNativeConfigurationGeneratorTests {
 	private void assertEquals(String expectedString, String filename) throws IOException, JSONException {
 		Path jsonFile = tempDir.resolve("META-INF").resolve("native-image").resolve(filename);
 		String content = new String(Files.readAllBytes(jsonFile));
-		JSONAssert.assertEquals(expectedString, content, JSONCompareMode.LENIENT);
+		JSONAssert.assertEquals(expectedString, content, JSONCompareMode.NON_EXTENSIBLE);
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/nativex/JavaSerializationHintsWriterTests.java

@@ -16,6 +16,8 @@
 
 package org.springframework.aot.nativex;
 
+import java.io.StringWriter;
+
 import org.json.JSONException;
 import org.junit.jupiter.api.Test;
 import org.skyscreamer.jsonassert.JSONAssert;
@@ -26,13 +28,11 @@ import org.springframework.aot.hint.TypeReference;
 import org.springframework.core.env.Environment;
 
 /**
- * Tests for {@link JavaSerializationHintsSerializer}.
+ * Tests for {@link JavaSerializationHintsWriter}.
  *
  * @author Sebastien Deleuze
  */
-public class JavaSerializationHintsSerializerTests {
-
-	private final JavaSerializationHintsSerializer serializer = new JavaSerializationHintsSerializer();
+public class JavaSerializationHintsWriterTests {
 
 	@Test
 	void empty() throws JSONException {
@@ -45,7 +45,7 @@ public class JavaSerializationHintsSerializerTests {
 		JavaSerializationHints hints = new JavaSerializationHints().registerType(TypeReference.of(String.class));
 		assertEquals("""
 				[
-					{ "name" : "java.lang.String" }
+					{ "name": "java.lang.String" }
 				]""", hints);
 	}
 
@@ -56,13 +56,16 @@ public class JavaSerializationHintsSerializerTests {
 				.registerType(TypeReference.of(Environment.class));
 		assertEquals("""
 				[
-					{ "name" : "java.lang.String" },
-					{ "name" : "org.springframework.core.env.Environment" }
+					{ "name": "java.lang.String" },
+					{ "name": "org.springframework.core.env.Environment" }
 				]""", hints);
 	}
 
 	private void assertEquals(String expectedString, JavaSerializationHints hints) throws JSONException {
-		JSONAssert.assertEquals(expectedString, serializer.serialize(hints), JSONCompareMode.LENIENT);
+		StringWriter out = new StringWriter();
+		BasicJsonWriter writer = new BasicJsonWriter(out, "\t");
+		JavaSerializationHintsWriter.INSTANCE.write(writer, hints);
+		JSONAssert.assertEquals(expectedString, out.toString(), JSONCompareMode.NON_EXTENSIBLE);
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/nativex/JsonUtilsTests.java

@@ -1,74 +0,0 @@
-/*
- * Copyright 2002-2022 the original author or authors.
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- *      https://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-
-package org.springframework.aot.nativex;
-
-import org.junit.jupiter.api.Test;
-
-import static org.assertj.core.api.Assertions.assertThat;
-
-/**
- * Tests for {@link JsonUtils}.
- *
- * @author Sebastien Deleuze
- */
-public class JsonUtilsTests {
-
-	@Test
-	void unescaped() {
-		assertThat(JsonUtils.escape("azerty")).isEqualTo("azerty");
-	}
-
-	@Test
-	void escapeDoubleQuote() {
-		assertThat(JsonUtils.escape("foo\"bar")).isEqualTo("foo\\\"bar");
-	}
-
-	@Test
-	void escapeBackslash() {
-		assertThat(JsonUtils.escape("foo\"bar")).isEqualTo("foo\\\"bar");
-	}
-
-	@Test
-	void escapeBackspace() {
-		assertThat(JsonUtils.escape("foo\bbar")).isEqualTo("foo\\bbar");
-	}
-
-	@Test
-	void escapeFormfeed() {
-		assertThat(JsonUtils.escape("foo\fbar")).isEqualTo("foo\\fbar");
-	}
-
-	@Test
-	void escapeNewline() {
-		assertThat(JsonUtils.escape("foo\nbar")).isEqualTo("foo\\nbar");
-	}
-
-	@Test
-	void escapeCarriageReturn() {
-		assertThat(JsonUtils.escape("foo\rbar")).isEqualTo("foo\\rbar");
-	}
-
-	@Test
-	void escapeTab() {
-		assertThat(JsonUtils.escape("foo\tbar")).isEqualTo("foo\\tbar");
-	}
-
-	@Test
-	void escapeUnicode() {
-		assertThat(JsonUtils.escape("foo\u001Fbar")).isEqualTo("foo\\u001fbar");
-	}
-}

spring-core/src/test/java/org/springframework/aot/nativex/ProxyHintsWriterTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.aot.nativex;
 
+import java.io.StringWriter;
 import java.util.function.Consumer;
 import java.util.function.Function;
 
@@ -27,13 +28,11 @@ import org.skyscreamer.jsonassert.JSONCompareMode;
 import org.springframework.aot.hint.ProxyHints;
 
 /**
- * Tests for {@link ProxyHintsSerializer}.
+ * Tests for {@link ProxyHintsWriter}.
  *
  * @author Sebastien Deleuze
  */
-public class ProxyHintsSerializerTests {
-
-	private final ProxyHintsSerializer serializer = new ProxyHintsSerializer();
+public class ProxyHintsWriterTests {
 
 	@Test
 	void empty() throws JSONException {
@@ -47,7 +46,7 @@ public class ProxyHintsSerializerTests {
 		hints.registerJdkProxy(Function.class);
 		assertEquals("""
 				[
-					{ "interfaces" : [ "java.util.function.Function" ] }
+					{ "interfaces": [ "java.util.function.Function" ] }
 				]""", hints);
 	}
 
@@ -58,14 +57,16 @@ public class ProxyHintsSerializerTests {
 		hints.registerJdkProxy(Function.class, Consumer.class);
 		assertEquals("""
 				[
-					{ "interfaces" : [ "java.util.function.Function" ] },
-					{ "interfaces" : [ "java.util.function.Function", "java.util.function.Consumer" ] }
+					{ "interfaces": [ "java.util.function.Function" ] },
+					{ "interfaces": [ "java.util.function.Function", "java.util.function.Consumer" ] }
 				]""", hints);
 	}
 
 	private void assertEquals(String expectedString, ProxyHints hints) throws JSONException {
-
-		JSONAssert.assertEquals(expectedString, serializer.serialize(hints), JSONCompareMode.LENIENT);
+		StringWriter out = new StringWriter();
+		BasicJsonWriter writer = new BasicJsonWriter(out, "\t");
+		ProxyHintsWriter.INSTANCE.write(writer, hints);
+		JSONAssert.assertEquals(expectedString, out.toString(), JSONCompareMode.NON_EXTENSIBLE);
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/nativex/ReflectionHintsWriterTests.java

@@ -16,6 +16,7 @@
 
 package org.springframework.aot.nativex;
 
+import java.io.StringWriter;
 import java.nio.charset.Charset;
 import java.util.Collections;
 import java.util.List;
@@ -33,13 +34,11 @@ import org.springframework.core.codec.StringDecoder;
 import org.springframework.util.MimeType;
 
 /**
- * Tests for {@link ReflectionHintsSerializer}.
+ * Tests for {@link ReflectionHintsWriter}.
  *
  * @author Sebastien Deleuze
  */
-public class ReflectionHintsSerializerTests {
-
-	private final ReflectionHintsSerializer serializer = new ReflectionHintsSerializer();
+public class ReflectionHintsWriterTests {
 
 	@Test
 	void empty() throws JSONException {
@@ -73,30 +72,30 @@ public class ReflectionHintsSerializerTests {
 		assertEquals("""
 				[
 					{
-						"name" : "org.springframework.core.codec.StringDecoder",
-						"condition" : { "typeReachable" : "java.lang.String" },
-						"allPublicFields" : true,
-						"allDeclaredFields" : true,
-						"queryAllPublicConstructors" : true,
-						"queryAllDeclaredConstructors" : true,
-						"allPublicConstructors" : true,
-						"allDeclaredConstructors" : true,
-						"queryAllPublicMethods" : true,
-						"queryAllDeclaredMethods" : true,
-						"allPublicMethods" : true,
-						"allDeclaredMethods" : true,
-						"allPublicClasses" : true,
-						"allDeclaredClasses" : true,
-						"fields" : [
-							{ "name" : "DEFAULT_CHARSET" },
-							{ "name" : "defaultCharset", "allowWrite" = true, "allowUnsafeAccess" = true }
+						"name": "org.springframework.core.codec.StringDecoder",
+						"condition": { "typeReachable": "java.lang.String" },
+						"allPublicFields": true,
+						"allDeclaredFields": true,
+						"queryAllPublicConstructors": true,
+						"queryAllDeclaredConstructors": true,
+						"allPublicConstructors": true,
+						"allDeclaredConstructors": true,
+						"queryAllPublicMethods": true,
+						"queryAllDeclaredMethods": true,
+						"allPublicMethods": true,
+						"allDeclaredMethods": true,
+						"allPublicClasses": true,
+						"allDeclaredClasses": true,
+						"fields": [
+							{ "name": "DEFAULT_CHARSET" },
+							{ "name": "defaultCharset", "allowWrite": true, "allowUnsafeAccess": true }
 						],
-						"methods" : [
-							{ "name" : "setDefaultCharset", "parameterTypes": [ "java.nio.charset.Charset" ] }
+						"methods": [
+							{ "name": "setDefaultCharset", "parameterTypes": [ "java.nio.charset.Charset" ] }
 						],
-						"queriedMethods" :  [
-							{ "name" : "<init>", "parameterTypes": [ "java.util.List", "boolean", "org.springframework.util.MimeType" ] },
-							{ "name" : "getDefaultCharset" }
+						"queriedMethods":  [
+							{ "name": "<init>", "parameterTypes": [ "java.util.List", "boolean", "org.springframework.util.MimeType" ] },
+							{ "name": "getDefaultCharset", "parameterTypes": [ ] }
 						]
 					}
 				]""", hints);
@@ -112,8 +111,8 @@ public class ReflectionHintsSerializerTests {
 
 		assertEquals("""
 				[
-					{ "name" : "java.lang.Integer" },
-					{ "name" : "java.lang.Long" }
+					{ "name": "java.lang.Integer" },
+					{ "name": "java.lang.Long" }
 				]""", hints);
 	}
 
@@ -158,6 +157,7 @@ public class ReflectionHintsSerializerTests {
 				]
 				""", hints);
 	}
+
 	@Test
 	void methodAndQueriedMethods() throws JSONException {
 		ReflectionHints hints = new ReflectionHints();
@@ -188,7 +188,10 @@ public class ReflectionHintsSerializerTests {
 	}
 
 	private void assertEquals(String expectedString, ReflectionHints hints) throws JSONException {
-		JSONAssert.assertEquals(expectedString, serializer.serialize(hints), JSONCompareMode.LENIENT);
+		StringWriter out = new StringWriter();
+		BasicJsonWriter writer = new BasicJsonWriter(out, "\t");
+		ReflectionHintsWriter.INSTANCE.write(writer, hints);
+		JSONAssert.assertEquals(expectedString, out.toString(), JSONCompareMode.NON_EXTENSIBLE);
 	}
 
 }

spring-core/src/test/java/org/springframework/aot/nativex/ResourceHintsWriterTests.java

@@ -16,7 +16,7 @@
 
 package org.springframework.aot.nativex;
 
-import java.io.IOException;
+import java.io.StringWriter;
 
 import org.json.JSONException;
 import org.junit.jupiter.api.Test;
@@ -26,22 +26,20 @@ import org.skyscreamer.jsonassert.JSONCompareMode;
 import org.springframework.aot.hint.ResourceHints;
 
 /**
- * Tests for {@link ResourceHintsSerializer}.
+ * Tests for {@link ResourceHintsWriter}.
  *
  * @author Sebastien Deleuze
  */
-public class ResourceHintsSerializerTests {
-
-	private final ResourceHintsSerializer serializer = new ResourceHintsSerializer();
+public class ResourceHintsWriterTests {
 
 	@Test
-	void empty() throws IOException, JSONException {
+	void empty() throws JSONException {
 		ResourceHints hints = new ResourceHints();
 		assertEquals("{}", hints);
 	}
 
 	@Test
-	void registerExactMatch() throws  JSONException {
+	void registerExactMatch() throws JSONException {
 		ResourceHints hints = new ResourceHints();
 		hints.registerPattern("com/example/test.properties");
 		hints.registerPattern("com/example/another.properties");
@@ -49,8 +47,8 @@ public class ResourceHintsSerializerTests {
 				{
 					"resources": {
 						"includes": [
-							{ "pattern" : "\\\\Qcom/example/test.properties\\\\E"},
-							{ "pattern" : "\\\\Qcom/example/another.properties\\\\E"}
+							{ "pattern": "\\\\Qcom/example/test.properties\\\\E"},
+							{ "pattern": "\\\\Qcom/example/another.properties\\\\E"}
 						]
 					}
 				}""", hints);
@@ -63,8 +61,8 @@ public class ResourceHintsSerializerTests {
 		assertEquals("""
 				{
 					"resources": {
-						"includes" : [
-							{ "pattern" : "\\\\Qcom/example/\\\\E.*\\\\Q.properties\\\\E"}
+						"includes": [
+							{ "pattern": "\\\\Qcom/example/\\\\E.*\\\\Q.properties\\\\E"}
 						]
 					}
 				}""", hints);
@@ -79,12 +77,12 @@ public class ResourceHintsSerializerTests {
 				{
 					"resources": {
 						"includes": [
-							{ "pattern" : "\\\\Qcom/example/\\\\E.*\\\\Q.properties\\\\E"},
-							{ "pattern" : "\\\\Qorg/example/\\\\E.*\\\\Q.properties\\\\E"}
+							{ "pattern": "\\\\Qcom/example/\\\\E.*\\\\Q.properties\\\\E"},
+							{ "pattern": "\\\\Qorg/example/\\\\E.*\\\\Q.properties\\\\E"}
 						],
 						"excludes": [
-							{ "pattern" : "\\\\Qcom/example/to-ignore.properties\\\\E"},
-							{ "pattern" : "\\\\Qorg/example/to-ignore.properties\\\\E"}
+							{ "pattern": "\\\\Qcom/example/to-ignore.properties\\\\E"},
+							{ "pattern": "\\\\Qorg/example/to-ignore.properties\\\\E"}
 						]
 					}
 				}""", hints);
@@ -97,8 +95,8 @@ public class ResourceHintsSerializerTests {
 		assertEquals("""
 				{
 					"resources": {
-						"includes" : [
-							{ "pattern" : "\\\\Qjava/lang/String.class\\\\E"}
+						"includes": [
+							{ "pattern": "\\\\Qjava/lang/String.class\\\\E"}
 						]
 					}
 				}""", hints);
@@ -112,14 +110,17 @@ public class ResourceHintsSerializerTests {
 		assertEquals("""
 				{
 					"bundles": [
-						{ "name" : "com.example.message"},
-						{ "name" : "com.example.message2"}
+						{ "name": "com.example.message"},
+						{ "name": "com.example.message2"}
 					]
 				}""", hints);
 	}
 
 	private void assertEquals(String expectedString, ResourceHints hints) throws JSONException {
-		JSONAssert.assertEquals(expectedString, serializer.serialize(hints), JSONCompareMode.LENIENT);
+		StringWriter out = new StringWriter();
+		BasicJsonWriter writer = new BasicJsonWriter(out, "\t");
+		ResourceHintsWriter.INSTANCE.write(writer, hints);
+		JSONAssert.assertEquals(expectedString, out.toString(), JSONCompareMode.NON_EXTENSIBLE);
 	}
 
 }