@ArezComponent public class UserRepository { // ... } @Observe public void onUserLoggedIn() { // ... } @Action public void fetchUserDetails() { // ... } @Observable private String username; <dependency> <groupId>org.realityforge.arez</groupId> <artifactId>arez-annotations</artifactId> <version>0.184</version> </dependency> apply plugin: 'java' dependencies { compile 'org.realityforge.arez:arez-annotations:0.184' } tasks.withType(JavaCompile) { options.annotationProcessorPath = configurations.compile options.compilerArgs << "-Aarez.component_validate:ERROR" }