Align keyColumn support in <generatedKey> tag

[dparo]

Standardize keyColumn handling in the tag for the following MyBatis Generator targets:

• MyBatis3Kotlin
• MyBatis3DynamicSql
• MyBatis3 ANNOTATEDMAPPER & MIXEDMAPPER

This update brings their behavior in line with the existing implementation in the MyBatis3 XMLMAPPER generator (refer to AbstractXmlElementGenerator::buildInitialInsert).

[Copilot]

Pull Request Overview

Standardize keyColumn handling in the <generatedKey> tag across MyBatis Generator targets to match XMLMAPPER behavior.

• Append keyColumn attribute to the @Options annotation using Optional and StringUtility.escapeString
• Introduce necessary imports (Optional, StringUtility) in Kotlin and dynamic SQL fragment generators
• Update Java mapper generator to include the same keyColumn logic

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
KotlinFragmentGenerator.java	Added Optional import and appended , keyColumn="…" to @Options
FragmentGenerator.java	Added Optional import and appended , keyColumn="…" to @Options
AbstractJavaMapperMethodGenerator.java	Added StringUtility import and appended , keyColumn="…" to @Options

Comments suppressed due to low confidence (3)

core/mybatis-generator-core/src/main/java/org/mybatis/generator/runtime/kotlin/elements/KotlinFragmentGenerator.java:193

• Add or update tests to cover scenarios where generatedKey.column is provided and omitted, ensuring the keyColumn attribute is correctly emitted or skipped.

sb.append(String.format(", keyColumn=\"%s\"", Optional.ofNullable(gk.getColumn()).map(StringUtility::escapeStringForKotlin).orElse(""))); 

core/mybatis-generator-core/src/main/java/org/mybatis/generator/codegen/mybatis3/javamapper/elements/AbstractJavaMapperMethodGenerator.java:43

• Missing import for java.util.Optional. Add import java.util.Optional; so that Optional.ofNullable(...) compiles.

import org.mybatis.generator.internal.util.StringUtility; 

core/mybatis-generator-core/src/main/java/org/mybatis/generator/runtime/kotlin/elements/KotlinFragmentGenerator.java:193

• [nitpick] Consider only appending the , keyColumn="…" segment when gk.getColumn() is non-null and non-empty to avoid emitting an empty keyColumn attribute.

sb.append(String.format(", keyColumn=\"%s\"", Optional.ofNullable(gk.getColumn()).map(StringUtility::escapeStringForKotlin).orElse("")));