Example of migration step by step to new technologies

Example of migration from Java project on Spring Boot 1.5 to Kotlin, Spring Boot 2 and after to Spring-webflux. And From Groovy Dsl to Kotlin Dsl in Gradle

Step 1

Simple project on Java and Spring Boot 1.5 with two controllers, service and in-memory repository. Project build by Groovy Dsl in Gradle

Step 2

Migrate to Spring Boot 2 and Junit 5. Main difference appears in tests and dependencies in build.gradle.

Step 3

Convert code to Kotlin, mostly by Intellij Idea and after clean code to Kotlin style. For mocking add mockito-kotlin library

Step 4

Convert code to webflux. For base project take this. Add several BeanPostProcessors to process spring annotations and add manual config loading. For the reason that yml processing classes I have found only in spring-boot-starter, it's needed to include this dependency to build.gradle

Step 5

Convert Gradle Dsl to Kotlin Dsl. For now worked only if moving Kotlin plugin to new Gradle plugin syntax.