Add then to the Java DSL

[mcruzdev]

Changes

This pull request allows us to jump to a task using then(String taskName):

    Workflow wf =
        FuncWorkflowBuilder.workflow("intelligent-newsletter")
            .tasks(
                consume("sendNewsletter", (String s) -> {}, String.class).then("otherTask"),
                function("nextTask", String::strip, String.class),
                function("otherTask", String::strip, String.class))
            .build();

Closes #1188

[ricardozanini]

Great work! Have you also checked how the mermaid diagram handles it? It's tangential to this work, but I can't remember whether I implemented it there.

[Copilot]

Pull request overview

This PR adds .then(...) chaining support to the experimental Java functional fluent DSL steps, allowing a task to direct workflow execution to a named next task (or a flow directive like END) without requiring Consumer.andThen() composition. This addresses issue #1188 by improving DSL ergonomics and adds tests to validate both model generation and runtime behavior.

Changes:

• Add then(String taskName) and then(FlowDirectiveEnum directive) to the fluent Step DSL so function(...) / consume(...) steps can set the task’s then directive.
• Extend DSL unit tests to assert the generated workflow model contains the expected then FlowDirective.
• Add an integration-style test in impl/test to validate runtime execution jumps/stops based on then(...).

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

File	Description
experimental/fluent/func/src/main/java/io/serverlessworkflow/fluent/func/dsl/Step.java	Adds then(...) chaining APIs that defer to TaskBaseBuilder.then(...) via queued post-configurers.
experimental/fluent/func/src/test/java/io/serverlessworkflow/fluent/func/FuncDSLTest.java	Adds unit tests verifying then(...) is serialized into the underlying task model for both function(...) and consume(...).
impl/test/src/test/java/io/serverlessworkflow/impl/test/WorkflowThenTest.java	Adds runtime tests asserting .then("task") skips the next task and .then(END) stops execution.
impl/test/pom.xml	Adds test-scope dependencies needed to build/execute workflows created with the experimental fluent func DSL and Java lambda execution.

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[Copilot]

WorkflowDefinition.instance(...) is started with Map.of(), but the first task is a typed Java String function/consumer (String.class). The Java lambda execution path converts the workflow input to the requested arg type via WorkflowModel.as(String.class), which will be empty for a JSON object, causing an exception before the then(...) behavior can be validated. Pass a String (e.g., a sample newsletter payload) as the workflow input, or set an inputFrom mapping that extracts a String from the provided map.

[mcruzdev]

@copilot open a new pull request to apply changes based on this feedback

[Copilot]

Same issue as earlier: the workflow instance is started with Map.of() but the first task is a typed String Java function (String.class), so input conversion will fail for a JSON object. Use a String input value (or add an inputFrom mapping) so this test reliably exercises then("otherTask").

[Copilot]

The workflow instance is started with Map.of(), but the first task is a typed String Java function (String.class), so the Java lambda executor will fail converting an object input to String. Provide a String input (or set inputFrom) so this test validates then(FlowDirectiveEnum.END) rather than failing on input conversion.