Compatibility & dependencies

All minor versions are backward compatible, meaning that you can upgrade to a newer minor version without breaking your code.

However, you should always check the changelog for any breaking changes.

Java Version

Fluxzero requires JDK 21 or higher to compile and run. It is actively tested on JDK 24 and remains compatible with recent versions.

Runtime Dependencies

Serialization

Dependency	Scope
`com.fasterxml.jackson.core:jackson-databind`	runtime
`com.fasterxml.jackson.datatype:jackson-datatype-jsr310`	runtime
`com.fasterxml.jackson.datatype:jackson-datatype-jdk8`	runtime
`org.msgpack:msgpack-core`	runtime
`org.lz4:lz4-java`	runtime

Payload Validation

Fluxzero includes its own SDK-focused Jakarta Validation implementation. Normal payload validation does not require Hibernate Validator, Expression Language, or their runtime dependencies.

Dependency	Scope
`jakarta.validation:jakarta.validation-api`	compile

Web and Transport

Dependency	Scope
`io.undertow:undertow-websockets-jsr`	runtime
`io.jooby:jooby`	runtime

Optional Integrations

Spring Support

Dependency	Scope
`org.springframework:spring-context`	optional
`org.springframework:spring-test`	test

Kotlin support

Fluxzero provides full support for Kotlin, including:

Use of data classes, which behave like Java records
Optional types (e.g., String?) instead of @Nullable
Seamless use of Kotlin-specific language features (e.g., when, sealed class, companion object)
Support for Class<T> parameters passed as MyClass::class or MyClass::class.java
Automatic recognition of Kotlin modules during deserialization (see below)

Automatic Jackson integration

Fluxzero includes Jackson Kotlin Module integration when available on the classpath. You do not need to manually register the module or use a service loader. If the jackson-module-kotlin dependency is present, it will be loaded dynamically for JSON (de)serialization.

Kotlin dependencies

Dependency	Scope
`com.fasterxml.jackson.module:jackson-module-kotlin`	optional
`org.jetbrains.kotlin:kotlin-stdlib-jdk8`	optional
`org.jetbrains.kotlin:kotlin-reflect`	optional
`org.jetbrains.kotlin:kotlin-test`	test

Test Dependencies

Dependency	Scope
`org.junit.jupiter:junit-jupiter-engine`	test
`org.junit.platform:junit-platform-launcher`	test
`org.mockito:mockito-core`	test
`org.jooq:joor`	test
`org.hamcrest:hamcrest-library`	test
`org.jboss.resteasy:resteasy-undertow`	test

ℹ️ Dependencies marked as optional are not required unless you use the corresponding integration. For example, Spring or Kotlin support is automatically detected when available but safely ignored otherwise.

Versioning Policy

Fluxzero aims to stay up-to-date with its core dependencies. We strive to:

Use the latest stable versions where possible,
Avoid breaking backward compatibility for common transitive consumers,
Update frequently, especially for frameworks like Jackson, Spring, Jakarta Validation, and JUnit.