Bump org.projectlombok:lombok in /plugins/gradle/example-server (#1236)

Bumps [org.projectlombok:lombok](https://github.com/projectlombok/lombok) from 1.18.26 to 1.18.28.
- [Release notes](https://github.com/projectlombok/lombok/releases)
- [Changelog](https://github.com/projectlombok/lombok/blob/master/doc/changelog.markdown)
- [Commits](https://github.com/projectlombok/lombok/compare/v1.18.26...v1.18.28)

---
updated-dependencies:
- dependency-name: org.projectlombok:lombok
  dependency-type: direct:production
  update-type: version-update:semver-patch
...
Signed-off-by: Ndependabot[bot] <support@github.com>
Co-authored-by: Ndependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

plugins/gradle/example-server/build.gradle

@@ -21,8 +21,8 @@ dependencies {
 
     implementation "javax.validation:validation-api:2.0.1.Final"
 
-    compileOnly "org.projectlombok:lombok:1.18.26"
-    annotationProcessor "org.projectlombok:lombok:1.18.26"
+    compileOnly "org.projectlombok:lombok:1.18.28"
+    annotationProcessor "org.projectlombok:lombok:1.18.28"
 
     implementation 'org.projectlombok:lombok-mapstruct-binding:0.2.0'