Provide default values for Kotlinx Serialization JSON properties

Closes gh-48097

module/spring-boot-kotlinx-serialization-json/src/main/java/org/springframework/boot/kotlinx/serialization/json/autoconfigure/KotlinxSerializationJsonAutoConfiguration.java

@@ -81,21 +81,20 @@ public final class KotlinxSerializationJsonAutoConfiguration {
 			KotlinxSerializationJsonProperties properties = this.properties;
 			PropertyMapper map = PropertyMapper.get();
 			map.from(properties::getNamingStrategy).to(setNamingStrategy(jsonBuilder));
-			map.from(properties::getPrettyPrint).to(jsonBuilder::setPrettyPrint);
-			map.from(properties::getLenient).to(jsonBuilder::setLenient);
-			map.from(properties::getIgnoreUnknownKeys).to(jsonBuilder::setIgnoreUnknownKeys);
-			map.from(properties::getEncodeDefaults).to(jsonBuilder::setEncodeDefaults);
-			map.from(properties::getExplicitNulls).to(jsonBuilder::setExplicitNulls);
-			map.from(properties::getCoerceInputValues).to(jsonBuilder::setCoerceInputValues);
-			map.from(properties::getAllowStructuredMapKeys).to(jsonBuilder::setAllowStructuredMapKeys);
-			map.from(properties::getAllowSpecialFloatingPointValues)
-				.to(jsonBuilder::setAllowSpecialFloatingPointValues);
+			map.from(properties::isPrettyPrint).to(jsonBuilder::setPrettyPrint);
+			map.from(properties::isLenient).to(jsonBuilder::setLenient);
+			map.from(properties::isIgnoreUnknownKeys).to(jsonBuilder::setIgnoreUnknownKeys);
+			map.from(properties::isEncodeDefaults).to(jsonBuilder::setEncodeDefaults);
+			map.from(properties::isExplicitNulls).to(jsonBuilder::setExplicitNulls);
+			map.from(properties::isCoerceInputValues).to(jsonBuilder::setCoerceInputValues);
+			map.from(properties::isAllowStructuredMapKeys).to(jsonBuilder::setAllowStructuredMapKeys);
+			map.from(properties::isAllowSpecialFloatingPointValues).to(jsonBuilder::setAllowSpecialFloatingPointValues);
 			map.from(properties::getClassDiscriminator).to(jsonBuilder::setClassDiscriminator);
 			map.from(properties::getClassDiscriminatorMode).to(jsonBuilder::setClassDiscriminatorMode);
-			map.from(properties::getDecodeEnumsCaseInsensitive).to(jsonBuilder::setDecodeEnumsCaseInsensitive);
-			map.from(properties::getUseAlternativeNames).to(jsonBuilder::setUseAlternativeNames);
-			map.from(properties::getAllowTrailingComma).to(jsonBuilder::setAllowTrailingComma);
-			map.from(properties::getAllowComments).to(jsonBuilder::setAllowComments);
+			map.from(properties::isDecodeEnumsCaseInsensitive).to(jsonBuilder::setDecodeEnumsCaseInsensitive);
+			map.from(properties::isUseAlternativeNames).to(jsonBuilder::setUseAlternativeNames);
+			map.from(properties::isAllowTrailingComma).to(jsonBuilder::setAllowTrailingComma);
+			map.from(properties::isAllowComments).to(jsonBuilder::setAllowComments);
 		}
 
 		private Consumer<KotlinxSerializationJsonProperties.JsonNamingStrategy> setNamingStrategy(JsonBuilder builder) {

module/spring-boot-kotlinx-serialization-json/src/main/java/org/springframework/boot/kotlinx/serialization/json/autoconfigure/KotlinxSerializationJsonProperties.java

@@ -38,83 +38,82 @@ public class KotlinxSerializationJsonProperties {
 	private @Nullable JsonNamingStrategy namingStrategy;
 
 	/**
-	 * Whether resulting JSON should be pretty-printed: formatted and optimized for human
-	 * readability.
+	 * Whether resulting JSON should be pretty-printed.
 	 */
-	private @Nullable Boolean prettyPrint;
+	private boolean prettyPrint;
 
 	/**
-	 * Enable lenient mode that removes JSON specification restriction (RFC-4627) and
-	 * makes parser more liberal to the malformed input.
+	 * Whether parser should operate in lenient mode, removing the JSON specification
+	 * restriction (RFC-4627) and being more liberal to malformed input.
 	 */
-	private @Nullable Boolean lenient;
+	private boolean lenient;
 
 	/**
 	 * Whether encounters of unknown properties in the input JSON should be ignored
 	 * instead of throwing SerializationException.
 	 */
-	private @Nullable Boolean ignoreUnknownKeys;
+	private boolean ignoreUnknownKeys;
 
 	/**
 	 * Whether default values of Kotlin properties should be encoded.
 	 */
-	private @Nullable Boolean encodeDefaults;
+	private boolean encodeDefaults;
 
 	/**
 	 * Whether null values should be encoded for nullable properties and must be present
 	 * in JSON object during decoding.
 	 */
-	private @Nullable Boolean explicitNulls;
+	private boolean explicitNulls = true;
 
 	/**
-	 * Enable coercing incorrect JSON values.
+	 * Whether to coerce incorrect JSON values.
 	 */
-	private @Nullable Boolean coerceInputValues;
+	private boolean coerceInputValues;
 
 	/**
-	 * Enable structured objects to be serialized as map keys by changing serialized form
-	 * of the map from JSON object (key-value pairs) to flat array like [k1, v1, k2, v2].
+	 * Whether to allow structured objects to be serialized as map keys by changing the
+	 * serialized form of the map from JSON object (key-value pairs) to flat array like
+	 * [k1, v1, k2, v2].
 	 */
-	private @Nullable Boolean allowStructuredMapKeys;
+	private boolean allowStructuredMapKeys;
 
 	/**
-	 * Whether to remove JSON specification restriction on special floating-point values
-	 * such as 'NaN' and 'Infinity' and enable their serialization and deserialization as
-	 * float literals without quotes.
+	 * Whether to remove the JSON specification restriction on special floating-point
+	 * values such as 'NaN' and 'Infinity' and allow their serialization and
+	 * deserialization as float literals without quotes.
 	 */
-	private @Nullable Boolean allowSpecialFloatingPointValues;
+	private boolean allowSpecialFloatingPointValues;
 
 	/**
 	 * Name of the class descriptor property for polymorphic serialization.
 	 */
-	private @Nullable String classDiscriminator;
+	private String classDiscriminator = "type";
 
 	/**
 	 * Defines which classes and objects should have class discriminator added to the
 	 * output.
 	 */
-	private @Nullable ClassDiscriminatorMode classDiscriminatorMode;
+	private ClassDiscriminatorMode classDiscriminatorMode = ClassDiscriminatorMode.POLYMORPHIC;
 
 	/**
-	 * Enable decoding enum values in a case-insensitive manner.
+	 * Whether enum values are decoded in a case-insensitive manner.
 	 */
-	private @Nullable Boolean decodeEnumsCaseInsensitive;
+	private boolean decodeEnumsCaseInsensitive;
 
 	/**
 	 * Whether Json instance makes use of JsonNames annotation.
 	 */
-	private @Nullable Boolean useAlternativeNames;
+	private boolean useAlternativeNames = true;
 
 	/**
-	 * Whether to allow parser to accept trailing (ending) commas in JSON objects and
-	 * arrays.
+	 * Whether to allow parser to accept trailing commas in JSON objects and arrays.
 	 */
-	private @Nullable Boolean allowTrailingComma;
+	private boolean allowTrailingComma;
 
 	/**
 	 * Whether to allow parser to accept C/Java-style comments in JSON input.
 	 */
-	private @Nullable Boolean allowComments;
+	private boolean allowComments;
 
 	public @Nullable JsonNamingStrategy getNamingStrategy() {
 		return this.namingStrategy;
@@ -124,115 +123,115 @@ public class KotlinxSerializationJsonProperties {
 		this.namingStrategy = namingStrategy;
 	}
 
-	public @Nullable Boolean getPrettyPrint() {
+	public boolean isPrettyPrint() {
 		return this.prettyPrint;
 	}
 
-	public void setPrettyPrint(@Nullable Boolean prettyPrint) {
+	public void setPrettyPrint(boolean prettyPrint) {
 		this.prettyPrint = prettyPrint;
 	}
 
-	public @Nullable Boolean getLenient() {
+	public boolean isLenient() {
 		return this.lenient;
 	}
 
-	public void setLenient(@Nullable Boolean lenient) {
+	public void setLenient(boolean lenient) {
 		this.lenient = lenient;
 	}
 
-	public @Nullable Boolean getIgnoreUnknownKeys() {
+	public boolean isIgnoreUnknownKeys() {
 		return this.ignoreUnknownKeys;
 	}
 
-	public void setIgnoreUnknownKeys(@Nullable Boolean ignoreUnknownKeys) {
+	public void setIgnoreUnknownKeys(boolean ignoreUnknownKeys) {
 		this.ignoreUnknownKeys = ignoreUnknownKeys;
 	}
 
-	public @Nullable Boolean getEncodeDefaults() {
+	public boolean isEncodeDefaults() {
 		return this.encodeDefaults;
 	}
 
-	public void setEncodeDefaults(@Nullable Boolean encodeDefaults) {
+	public void setEncodeDefaults(boolean encodeDefaults) {
 		this.encodeDefaults = encodeDefaults;
 	}
 
-	public @Nullable Boolean getExplicitNulls() {
+	public boolean isExplicitNulls() {
 		return this.explicitNulls;
 	}
 
-	public void setExplicitNulls(@Nullable Boolean explicitNulls) {
+	public void setExplicitNulls(boolean explicitNulls) {
 		this.explicitNulls = explicitNulls;
 	}
 
-	public @Nullable Boolean getCoerceInputValues() {
+	public boolean isCoerceInputValues() {
 		return this.coerceInputValues;
 	}
 
-	public void setCoerceInputValues(@Nullable Boolean coerceInputValues) {
+	public void setCoerceInputValues(boolean coerceInputValues) {
 		this.coerceInputValues = coerceInputValues;
 	}
 
-	public @Nullable Boolean getAllowStructuredMapKeys() {
+	public boolean isAllowStructuredMapKeys() {
 		return this.allowStructuredMapKeys;
 	}
 
-	public void setAllowStructuredMapKeys(@Nullable Boolean allowStructuredMapKeys) {
+	public void setAllowStructuredMapKeys(boolean allowStructuredMapKeys) {
 		this.allowStructuredMapKeys = allowStructuredMapKeys;
 	}
 
-	public @Nullable Boolean getAllowSpecialFloatingPointValues() {
+	public boolean isAllowSpecialFloatingPointValues() {
 		return this.allowSpecialFloatingPointValues;
 	}
 
-	public void setAllowSpecialFloatingPointValues(@Nullable Boolean allowSpecialFloatingPointValues) {
+	public void setAllowSpecialFloatingPointValues(boolean allowSpecialFloatingPointValues) {
 		this.allowSpecialFloatingPointValues = allowSpecialFloatingPointValues;
 	}
 
-	public @Nullable String getClassDiscriminator() {
+	public String getClassDiscriminator() {
 		return this.classDiscriminator;
 	}
 
-	public void setClassDiscriminator(@Nullable String classDiscriminator) {
+	public void setClassDiscriminator(String classDiscriminator) {
 		this.classDiscriminator = classDiscriminator;
 	}
 
-	public @Nullable ClassDiscriminatorMode getClassDiscriminatorMode() {
+	public ClassDiscriminatorMode getClassDiscriminatorMode() {
 		return this.classDiscriminatorMode;
 	}
 
-	public void setClassDiscriminatorMode(@Nullable ClassDiscriminatorMode classDiscriminatorMode) {
+	public void setClassDiscriminatorMode(ClassDiscriminatorMode classDiscriminatorMode) {
 		this.classDiscriminatorMode = classDiscriminatorMode;
 	}
 
-	public @Nullable Boolean getDecodeEnumsCaseInsensitive() {
+	public boolean isDecodeEnumsCaseInsensitive() {
 		return this.decodeEnumsCaseInsensitive;
 	}
 
-	public void setDecodeEnumsCaseInsensitive(@Nullable Boolean decodeEnumsCaseInsensitive) {
+	public void setDecodeEnumsCaseInsensitive(boolean decodeEnumsCaseInsensitive) {
 		this.decodeEnumsCaseInsensitive = decodeEnumsCaseInsensitive;
 	}
 
-	public @Nullable Boolean getUseAlternativeNames() {
+	public boolean isUseAlternativeNames() {
 		return this.useAlternativeNames;
 	}
 
-	public void setUseAlternativeNames(@Nullable Boolean useAlternativeNames) {
+	public void setUseAlternativeNames(boolean useAlternativeNames) {
 		this.useAlternativeNames = useAlternativeNames;
 	}
 
-	public @Nullable Boolean getAllowTrailingComma() {
+	public boolean isAllowTrailingComma() {
 		return this.allowTrailingComma;
 	}
 
-	public void setAllowTrailingComma(@Nullable Boolean allowTrailingComma) {
+	public void setAllowTrailingComma(boolean allowTrailingComma) {
 		this.allowTrailingComma = allowTrailingComma;
 	}
 
-	public @Nullable Boolean getAllowComments() {
+	public boolean isAllowComments() {
 		return this.allowComments;
 	}
 
-	public void setAllowComments(@Nullable Boolean allowComments) {
+	public void setAllowComments(boolean allowComments) {
 		this.allowComments = allowComments;
 	}
 

module/spring-boot-kotlinx-serialization-json/src/test/java/org/springframework/boot/kotlinx/serialization/json/autoconfigure/KotlinxSerializationJsonPropertiesTests.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2012-present 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.boot.kotlinx.serialization.json.autoconfigure;
+
+import kotlinx.serialization.json.Json;
+import kotlinx.serialization.json.JsonBuilder;
+import org.jspecify.annotations.Nullable;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.EnumSource;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+/**
+ * Tests for {@link KotlinxSerializationJsonProperties}.
+ *
+ * @author Andy Wilkinson
+ */
+class KotlinxSerializationJsonPropertiesTests {
+
+	@ParameterizedTest
+	@EnumSource
+	void defaultsAreAligned(JsonBuilderSettings settings) {
+		JsonBuilder jsonBuilder = new JsonBuilder(Json.Default);
+		KotlinxSerializationJsonProperties properties = new KotlinxSerializationJsonProperties();
+		assertThat(settings.propertyGetter.get(properties)).isEqualTo(settings.jsonBuilderGetter.get(jsonBuilder));
+	}
+
+	private enum JsonBuilderSettings {
+
+		ALLOW_COMMENTS(KotlinxSerializationJsonProperties::isAllowComments, JsonBuilder::getAllowComments),
+
+		ALLOW_SPECIAL_FLOATING_POINT_VALUES(KotlinxSerializationJsonProperties::isAllowSpecialFloatingPointValues,
+				JsonBuilder::getAllowSpecialFloatingPointValues),
+
+		ALLOW_STRUCTURED_MAP_KEYS(KotlinxSerializationJsonProperties::isAllowStructuredMapKeys,
+				JsonBuilder::getAllowStructuredMapKeys),
+
+		ALLOW_TRAILING_COMMA(KotlinxSerializationJsonProperties::isAllowTrailingComma,
+				JsonBuilder::getAllowTrailingComma),
+
+		CLASS_DISCRIMINATOR(KotlinxSerializationJsonProperties::getClassDiscriminator,
+				JsonBuilder::getClassDiscriminator),
+
+		CLASS_DISCRIMINATOR_MODE(KotlinxSerializationJsonProperties::getClassDiscriminatorMode,
+				JsonBuilder::getClassDiscriminatorMode),
+
+		COERCE_INPUT_VALUES(KotlinxSerializationJsonProperties::isCoerceInputValues, JsonBuilder::getCoerceInputValues),
+
+		DECODE_ENUMS_CASE_INSENSITIVE(KotlinxSerializationJsonProperties::isDecodeEnumsCaseInsensitive,
+				JsonBuilder::getDecodeEnumsCaseInsensitive),
+
+		ENCODE_DEFAULTS(KotlinxSerializationJsonProperties::isEncodeDefaults, JsonBuilder::getEncodeDefaults),
+
+		EXPLICIT_NULLS(KotlinxSerializationJsonProperties::isExplicitNulls, JsonBuilder::getExplicitNulls),
+
+		IGNORE_UNKNOWN_KEYS(KotlinxSerializationJsonProperties::isIgnoreUnknownKeys, JsonBuilder::getIgnoreUnknownKeys),
+
+		LENIENT(KotlinxSerializationJsonProperties::isLenient, JsonBuilder::isLenient),
+
+		NAMING_STRATEGY(KotlinxSerializationJsonProperties::getNamingStrategy, JsonBuilder::getNamingStrategy),
+
+		PRETTY_PRINT(KotlinxSerializationJsonProperties::isPrettyPrint, JsonBuilder::getPrettyPrint),
+
+		USE_ALTERNATIVE_NAMES(KotlinxSerializationJsonProperties::isUseAlternativeNames,
+				JsonBuilder::getUseAlternativeNames);
+
+		private final Accessor<KotlinxSerializationJsonProperties, ?> propertyGetter;
+
+		private final Accessor<JsonBuilder, ?> jsonBuilderGetter;
+
+		JsonBuilderSettings(Accessor<KotlinxSerializationJsonProperties, @Nullable Object> propertyGetter,
+				Accessor<JsonBuilder, @Nullable Object> jsonBuilderGetter) {
+			this.propertyGetter = propertyGetter;
+			this.jsonBuilderGetter = jsonBuilderGetter;
+		}
+
+		private interface Accessor<S, @Nullable P extends @Nullable Object> {
+
+			@Nullable P get(S source);
+
+		}
+
+	}
+
+}