[Processor] Simplify default value handling for strings

This commit simplifies the usage of `defaultValue` in `PropertyMapping`. String default values no longer need to be wrapped in escaped quotes. The processor now automatically adds quotes if the target type is a `String`.

Key changes:
- Updated the processor to wrap the `defaultValue` in quotes if the target property is a String and the value isn't already quoted.
- Removed the now-unnecessary escaped quotes from `defaultValue` assignments in all sample and test files.
- Clarified the documentation in the `PropertyMapping` annotation to reflect this simplified usage.

Author: jacksever

README.md

@@ -238,7 +238,7 @@ import io.github.jacksever.automapper.annotation.PropertyMapping
         // Renames 'id' to 'userId'
         PropertyMapping(from = "id", to = "userId"),
         // Provides a default value for 'address' if it's null
-        PropertyMapping(from = "address", defaultValue = "\"Unknown\"")
+        PropertyMapping(from = "address", defaultValue = "Unknown")
     ]
 )
 fun userMapper(user: User): UserEntity

automapper/annotation/src/commonMain/kotlin/io/github/jacksever/automapper/annotation/PropertyMapping.kt

@@ -22,7 +22,7 @@ package io.github.jacksever.automapper.annotation
  * @property from name of the property in the source class
  * @property to name of the property in the target class. If omitted, it is assumed to be the same as [from]
  * @property defaultValue string literal to be used as a default value if the source property is null and the target is not nullable.
- * For example, `defaultValue = "\"\""` for an empty string, or `defaultValue = "0L"` for a Long
+ * For example, `defaultValue = ""` for an empty string, or `defaultValue = "0L"` for a Long
  */
 @Target
 @Retention(AnnotationRetention.SOURCE)

automapper/processor/src/main/kotlin/io/github/jacksever/automapper/processor/helper/ParameterHelper.kt

@@ -63,7 +63,7 @@ internal object ParameterHelper {
                 val conversion = getConversionExpression(
                     sourceType = sourceType,
                     targetType = targetType,
-                    defaultValue = mapping?.defaultValue.orEmpty(),
+                    defaultValue = mapping?.defaultValue,
                 )
 
                 add("$targetParamName = ${sourceProperty.simpleName.asString()}$conversion")
@@ -107,7 +107,7 @@ internal object ParameterHelper {
                     "!!$conversion"
                 } else {
                     // A default value is provided, use Elvis operator
-                    "$conversion ?: $defaultValue"
+                    "$conversion ?: ${formatDefaultValue(targetType, defaultValue)}"
                 }
             } else {
                 if (conversion.isNotEmpty()) {
@@ -220,6 +220,19 @@ internal object ParameterHelper {
         }
     }
 
+    /**
+     * Formats the default value string based on the target type
+     */
+    private fun formatDefaultValue(targetType: KSType, defaultValue: String): String {
+        val isString = targetType.declaration.simpleName.asString() == "String"
+
+        return if (isString && !defaultValue.startsWith(prefix = "\"")) {
+            "\"$defaultValue\""
+        } else {
+            defaultValue
+        }
+    }
+
     /**
      * Checks if the class declaration corresponds to a List type (Kotlin or Java)
      */

sample/src/commonMain/kotlin/io/github/jacksever/automapper/sample/mapper/MapperModule.kt

@@ -48,8 +48,8 @@ internal interface MapperModule {
     @AutoMapper(
         propertyMappings = [
             PropertyMapping(from = "id", to = "userId"),
-            PropertyMapping(from = "address", defaultValue = "\"Unknown\""),
-            PropertyMapping(from = "middleName", to = "patronymic", defaultValue = "\"N/A\"")
+            PropertyMapping(from = "address", defaultValue = "Unknown"),
+            PropertyMapping(from = "middleName", to = "patronymic", defaultValue = "N/A")
         ]
     )
     fun userMapper(user: User): UserEntity
@@ -63,7 +63,7 @@ internal interface MapperModule {
     @AutoMapper(
         reversible = false,
         propertyMappings = [
-            PropertyMapping(from = "address", defaultValue = "\"Unknown\""),
+            PropertyMapping(from = "address", defaultValue = "Unknown"),
         ]
     )
     fun uiUserMapper(user: User): UiUser

sample/src/jvmTest/kotlin/io/github/jacksever/automapper/sample/mapper/DataClassTestMapperModule.kt

@@ -63,7 +63,7 @@ internal interface DataClassTestMapperModule {
         propertyMappings = [
             PropertyMapping(from = "legacyId", to = "id"),
             PropertyMapping(from = "statusNum", to = "statusText"),
-            PropertyMapping(from = "content", defaultValue = "\"Empty\""),
+            PropertyMapping(from = "content", defaultValue = "Empty"),
         ]
     )
     fun complexMapper(from: ComplexSource): ComplexTarget
@@ -78,7 +78,7 @@ internal interface DataClassTestMapperModule {
 
     @AutoMapper(
         propertyMappings = [
-            PropertyMapping(from = "description", defaultValue = "\"Default\""),
+            PropertyMapping(from = "description", defaultValue = "Default"),
         ]
     )
     fun defaultValueMapper(from: DefaultValueSource): DefaultValueTarget