[Fix #1601] Implement then on catch

[fjtirado]

Fix #1601

[Copilot]

Pull request overview

Adds support for a then directive on try...catch blocks (issue #1601), and refactors the executor builder generics to preserve concrete executor types through the builder hierarchy.

Changes:

• Implement handling of catch.then in TryExecutor by building a separate catch transition and applying it when a catch matches.
• Refactor RegularTaskExecutorBuilder to be generic on both task type and executor type, updating all affected executors’ builders accordingly.
• Add a workflow sample and extend an existing parameterized test to cover catch.then.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
impl/test/src/test/resources/workflows-samples/try-catch-match-then.yaml	Adds a sample workflow that uses catch.then to redirect execution after a handled error.
impl/test/src/test/java/io/serverlessworkflow/impl/test/RetryTimeoutTest.java	Extends parameterized coverage to include the new catch.then sample.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/WaitExecutor.java	Updates builder type parameters to match the new RegularTaskExecutorBuilder<T, V> signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/TryExecutor.java	Implements catch.then transition wiring and alters execution/transition behavior for try/catch.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/SetExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/RunTaskExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/RegularTaskExecutor.java	Refactors the regular executor builder to carry the concrete executor type and simplifies execute chaining.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/RaiseExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/ListenExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/ForkExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/ForExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/EmitExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/DoExecutor.java	Updates builder generics to the new base builder signature.
impl/core/src/main/java/io/serverlessworkflow/impl/executors/CallTaskExecutor.java	Updates builder generics to the new base builder signature.

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[Copilot]

Pull request overview

Copilot reviewed 15 out of 15 changed files in this pull request and generated no new comments.

Suppressed comments (2)

impl/test/src/test/resources/workflows-samples/try-catch-retry-inline-then.yaml:21

• The catch.then block is currently written as a nested mapping (then: followed by an indented bare key), which YAML parses as an object (e.g., {endGracefully: null}) rather than the intended scalar flow directive. This is inconsistent with the other sample (then: endGracefully) and can break parsing/binding to FlowDirective.

        then:
            endGracefully

impl/core/src/main/java/io/serverlessworkflow/impl/executors/TryExecutor.java:80

• catchTransitionBuilder is never initialized, so if this builder is built without a prior connect(...) call (e.g., TaskExecutorHelper.createBranchList(...) builds executors without calling connect), buildTransition(...) will throw a NullPointerException when it calls catchTransitionBuilder.map(...). Initialize it to Optional.empty() so buildTransition(...) is safe regardless of whether connect(...) ran.

    private final FlowDirective catchDirective;
    private Optional<TransitionInfoBuilder> catchTransitionBuilder;
    private String errorVariable;