DATACMNS-1322 - Cleanup refactorings.

Add missing since tags. Extract methods to maintain single abstraction level per method. Move visitDefaultValue from ClassGeneratingPropertyAccessorFactory to BytecodeUtil. Extend Javadoc.

src/main/java/org/springframework/data/mapping/PersistentProperty.java

@@ -114,10 +114,27 @@ public interface PersistentProperty<P extends PersistentProperty<P>> {
 	}
 
 	/**
-	 * Returns the wither method to set a property value on a new object instance. Might return {@literal null} in case
-	 * there is no wither available.
+	 * Returns the wither {@link Method} to set a property value on a new object instance. Might return {@literal null} in
+	 * case there is no wither available.
+	 * <p/>
+	 * Wither {@link Method methods} are property-bound instance {@link Method methods} that accept a single argument of
+	 * the property type creating a new object instance.
 	 *
-	 * @return the wither method to set a property value on a new object instance if available, otherwise {@literal null}.
+	 * <pre class="code">
+	 * class Person {
+	 * 	final String id;
+	 * 	final String name;
+	 *
+	 * 	// …
+	 *
+	 * 	Person withName(String name) {
+	 * 		return new Person(this.id, name);
+	 * 	}
+	 * }
+	 * </pre>
+	 *
+	 * @return the wither {@link Method} to set a property value on a new object instance if available, otherwise
+	 *         {@literal null}.
 	 * @since 2.1
 	 */
 	@Nullable
@@ -247,6 +264,7 @@ public interface PersistentProperty<P extends PersistentProperty<P>> {
 	 * {@code final}.
 	 *
 	 * @return
+	 * @see java.lang.reflect.Modifier#isFinal(int)
 	 * @since 2.1
 	 */
 	boolean isImmutable();
@@ -366,7 +384,7 @@ public interface PersistentProperty<P extends PersistentProperty<P>> {
 
 	/**
 	 * Return the type the property refers to in case it's an association.
-	 * 
+	 *
 	 * @return the type the property refers to in case it's an association or {@literal null} in case it's not an
 	 *         association, the target entity type is not explicitly defined (either explicitly or through the property
 	 *         type itself).

src/main/java/org/springframework/data/mapping/PersistentPropertyAccessor.java

@@ -123,7 +123,8 @@ public interface PersistentPropertyAccessor {
 	}
 
 	/**
-	 * Returns the underlying bean. May change between {@link #setProperty(PersistentProperty, Object)} calls.
+	 * Returns the underlying bean. The actual instance may change between
+	 * {@link #setProperty(PersistentProperty, Object)} calls.
 	 *
 	 * @return will never be {@literal null}.
 	 */

src/main/java/org/springframework/data/mapping/model/BeanWrapper.java

@@ -160,37 +160,62 @@ class BeanWrapper<T> implements PersistentPropertyAccessor {
 
 	/**
 	 * Utility class to leverage Kotlin's copy method for immutable data classes.
+	 *
+	 * @since 2.1
 	 */
 	static class KotlinCopyUtil {
 
+		/**
+		 * Set a single property by calling {@code copy(…)} on a Kotlin data class. Copying creates a new instance that
+		 * holds all values of the original instance and the newly set {@link PersistentProperty} value.
+		 *
+		 * @see KCallable#callBy(Map)
+		 */
 		static <T> Object setProperty(PersistentProperty<?> property, T bean, @Nullable Object value) {
 
 			Class<?> type = property.getOwner().getType();
 			KClass<?> kotlinClass = JvmClassMappingKt.getKotlinClass(type);
+			KCallable<?> copy = getCopyMethod(kotlinClass);
+
+			if (copy == null) {
+				throw new UnsupportedOperationException(String.format(
+						"Kotlin class %s has no .copy(…) method. Cannot set property %s!", type.getName(), property.getName()));
+			}
+
+			return copy.callBy(getCallArgs(copy, property, bean, value));
+		}
+
+		private static <T> Map<KParameter, Object> getCallArgs(KCallable<?> callable, PersistentProperty<?> property,
+				T bean, @Nullable Object value) {
 
 			Map<KParameter, Object> args = new LinkedHashMap<>(2, 1);
-			for (KCallable<?> kCallable : kotlinClass.getMembers()) {
 
-				List<KParameter> parameters = kCallable.getParameters();
+			List<KParameter> parameters = callable.getParameters();
 
-				for (KParameter parameter : parameters) {
+			for (KParameter parameter : parameters) {
 
-					if (parameter.getKind() == Kind.INSTANCE) {
-						args.put(parameter, bean);
-					}
-
-					if (parameter.getKind() == Kind.VALUE && parameter.getName().equals(property.getName())) {
-						args.put(parameter, value);
-					}
+				if (parameter.getKind() == Kind.INSTANCE) {
+					args.put(parameter, bean);
 				}
 
+				if (parameter.getKind() == Kind.VALUE && parameter.getName().equals(property.getName())) {
+					args.put(parameter, value);
+				}
+			}
+			return args;
+		}
+
+		@Nullable
+		private static KCallable<?> getCopyMethod(KClass<?> kotlinClass) {
+
+			for (KCallable<?> kCallable : kotlinClass.getMembers()) {
+
 				if (kCallable.getName().equals("copy")) {
-					return kCallable.callBy(args);
+					return kCallable;
 				}
 			}
 
-			throw new UnsupportedOperationException(String.format(
-					"Kotlin class %s has no .copy(…) method. Cannot set property %s!", type.getName(), property.getName()));
+			return null;
 		}
 	}
 }

src/main/java/org/springframework/data/mapping/model/BytecodeUtil.java

@@ -22,12 +22,14 @@ import lombok.experimental.UtilityClass;
 import java.lang.reflect.Modifier;
 
 import org.springframework.asm.MethodVisitor;
+import org.springframework.asm.Opcodes;
 import org.springframework.asm.Type;
 
 /**
  * Utility methods used for ASM-based class generation during runtime.
  *
  * @author Mark Paluch
+ * @since 2.1
  */
 @UtilityClass
 class BytecodeUtil {
@@ -81,7 +83,7 @@ class BytecodeUtil {
 	 *
 	 * @param in the input type
 	 * @param out the expected output type
-	 * @param visitor
+	 * @param visitor must not be {@literal null}.
 	 */
 	static void autoboxIfNeeded(Class<?> in, Class<?> out, MethodVisitor visitor) {
 
@@ -154,7 +156,7 @@ class BytecodeUtil {
 	 * Checks whether the class is accessible by inspecting modifiers (i.e. whether the class is {@code private}).
 	 *
 	 * @param type must not be {@literal null}.
-	 * @return
+	 * @return {@literal true} if the {@link Class} is accessible.
 	 * @see Modifier#isPrivate(int)
 	 */
 	static boolean isAccessible(Class<?> type) {
@@ -165,7 +167,7 @@ class BytecodeUtil {
 	 * Checks whether the class is accessible by inspecting modifiers (i.e. whether the class is {@code private}).
 	 *
 	 * @param type must not be {@literal null}.
-	 * @return
+	 * @return {@literal true} if the {@code modifiers} do not indicate the private flag.
 	 * @see Modifier#isPrivate(int)
 	 */
 	static boolean isAccessible(int modifiers) {
@@ -177,7 +179,7 @@ class BytecodeUtil {
 	 * {@literal private}/{@literal protected}/{@literal public}).
 	 *
 	 * @param type must not be {@literal null}.
-	 * @return
+	 * @return {@literal true} if the {@code modifiers} indicate {@literal default}.
 	 * @see Modifier#isPrivate(int)
 	 */
 	static boolean isDefault(int modifiers) {
@@ -188,12 +190,18 @@ class BytecodeUtil {
 	 * Create a reference type name in the form of {@literal Ljava/lang/Object;}.
 	 *
 	 * @param type must not be {@literal null}.
-	 * @return
+	 * @return reference type name in the form of {@literal Ljava/lang/Object;}.
 	 */
 	static String referenceName(Class<?> type) {
 		return type.isArray() ? Type.getInternalName(type) : referenceName(Type.getInternalName(type));
 	}
 
+	/**
+	 * Create a reference type name in the form of {@literal Ljava/lang/Object;}.
+	 *
+	 * @param internalTypeName must not be {@literal null}.
+	 * @return reference type name in the form of {@literal Ljava/lang/Object;}.
+	 */
 	static String referenceName(String internalTypeName) {
 		return String.format("L%s;", internalTypeName);
 	}
@@ -244,4 +252,39 @@ class BytecodeUtil {
 
 		return referenceName(type);
 	}
+
+	/**
+	 * Create a byte code instruction that puts a default value for {@link Class} on the stack. Primitive types default to
+	 * zero, reference types use {@literal null}.
+	 *
+	 * @param parameterType must not be {@literal null}.
+	 * @param mv must not be {@literal null}.
+	 */
+	static void visitDefaultValue(Class<?> parameterType, MethodVisitor mv) {
+
+		if (parameterType.isPrimitive()) {
+
+			if (parameterType == Integer.TYPE || parameterType == Short.TYPE || parameterType == Boolean.TYPE) {
+				mv.visitInsn(Opcodes.ICONST_0);
+			}
+
+			if (parameterType == Long.TYPE) {
+				mv.visitInsn(Opcodes.LCONST_0);
+			}
+
+			if (parameterType == Double.TYPE) {
+				mv.visitInsn(Opcodes.DCONST_0);
+			}
+
+			if (parameterType == Float.TYPE) {
+				mv.visitInsn(Opcodes.FCONST_0);
+			}
+
+			if (parameterType == Character.TYPE || parameterType == Byte.TYPE) {
+				mv.visitIntInsn(Opcodes.BIPUSH, 0);
+			}
+		} else {
+			mv.visitInsn(Opcodes.ACONST_NULL);
+		}
+	}
 }

src/main/java/org/springframework/data/mapping/model/Property.java

@@ -83,7 +83,8 @@ public class Property {
 
 	private static Optional<Method> findWither(TypeInformation<?> owner, String propertyName, Class<?> rawType) {
 
-		Method method = ReflectionUtils.findMethod(owner.getType(), "with" + StringUtils.capitalize(propertyName), rawType);
+		Method method = ReflectionUtils.findMethod(owner.getType(),
+				String.format("with%s", StringUtils.capitalize(propertyName)), rawType);
 
 		if (method != null && owner.isAssignableFrom(owner.getReturnType(method))) {
 			return Optional.of(method);
@@ -147,7 +148,7 @@ public class Property {
 	 */
 	public static boolean supportsStandalone(PropertyDescriptor descriptor) {
 
-		Assert.notNull(descriptor, "PropertDescriptor must not be null!");
+		Assert.notNull(descriptor, "PropertyDescriptor must not be null!");
 
 		return descriptor.getPropertyType() != null;
 	}

src/main/java/org/springframework/data/util/ReflectionUtils.java

@@ -410,6 +410,7 @@ public class ReflectionUtils {
 	 *
 	 * @param type must not be {@literal null}.
 	 * @return boxed primitive default value.
+	 * @since 2.1
 	 */
 	public static Object getPrimitiveDefault(Class<?> type) {