Fix javadoc generation

Author: larsgrefer

documentation/build.gradle

@@ -32,10 +32,15 @@ dependencies {
     javadocClasspath "org.jacoco:org.jacoco.ant:${org.gradle.testing.jacoco.plugins.JacocoPlugin.DEFAULT_JACOCO_VERSION}"
     javadocClasspath "org.apache.maven.plugins:maven-plugin-plugin:3.15.1"
     javadocClasspath 'net.sourceforge.plantuml:plantuml:1.2025.2'
+    javadocClasspath 'org.projectlombok:lombok:1.18.36'
 
     asciidoctorExt "io.spring.asciidoctor:spring-asciidoctor-extensions-block-switch:0.6.3"
 }
 
+tasks.named("javadoc", Javadoc) {
+    failOnError = true
+}
+
 tasks.register("docsZip", Zip) {
     group = 'build'
     archiveClassifier = 'docs'