Fixes: Enhance Kotlin Support for Suppliers, Functions, and Consumers #1277

[apoupard]

Description:

This merge request aims to enhance and solidify Kotlin support within Spring Cloud Function. It addresses several identified issues related to the handling of various Kotlin features, including suspend functions, Flow types, and different functional arities/signatures for Suppliers, Functions, and Consumers.

Recent compatibility testing highlighted a number of scenarios where Kotlin function declarations were not being processed as expected, leading to runtime exceptions and test failures. This MR introduces fixes and improvements to the spring-cloud-function-context to better interpret and manage diverse Kotlin functional styles.

Key Changes:

• Enhanced Kotlin Arity Handling: The spring-cloud-function-context has been refactored to more comprehensively handle various declaration combinations for Kotlin functions, consumers, and suppliers.
• New Arity Tests: A comprehensive suite of tests has been added to the spring-cloud-function-kotlin module. These tests cover a wide range of Kotlin function, consumer, and supplier declarations to ensure their correct behavior and to help identify areas for further improvement.
• Unit Tests for Arity and Wrappers: Additional unit tests have been introduced to verify the core logic for Kotlin arity handling and associated wrapper mechanisms. These tests cover catalogue registration and native type casting.

Summary of Addressed Issues from Testing:

The changes in this MR specifically target issues observed during testing, such as:

• UnsupportedOperationException and NullPointerException related to suspend function handling.
• ClassCastException when dealing with kotlinx.coroutines.flow.Flow and org.springframework.messaging.Message types.
• DecodingException for certain reactive types like Flow.

By addressing these points, this MR significantly improves the robustness and usability of Spring Cloud Function for Kotlin developers, aiming to provide a more seamless and first-class experience.

[apoupard]

About the DCO task fail, I have update the email to [email protected].
All commits have
Signed-off-by: Adrien [email protected]

[artembilan]

Signed-off-by: Adrien [email protected]

It has to container your legal name - full legal name.
Consider to squash all commits and force-push only one with correct sign-off.
Thanks

[apoupard]

Done, thanks

[olegz]

@apoupard It doesn't build

Basically when I try a full build here is what i see pretty much right away

. . .
[ERROR] /***/spring-cloud-function/spring-cloud-function-context/src/main/kotlin/org/springframework/cloud/function/context/config/TypeUtils.kt:[81,1] Conflicting overloads: public fun isContinuationUnitType(type: Type): Boolean defined in org.springframework.cloud.function.context.config in file TypeUtils.kt, public fun isContinuationUnitType(type: Type): Boolean defined in org.springframework.cloud.function.context.config
[ERROR] /***/spring-cloud-function/spring-cloud-function-context/src/main/kotlin/org/springframework/cloud/function/context/config/TypeUtils.kt:[85,1] Conflicting overloads: public fun isContinuationFlowType(type: Type): Boolean defined in org.springframework.cloud.function.context.config in file TypeUtils.kt, public fun isContinuationFlowType(type: Type): Boolean defined in org.springframework.cloud.function.context.config
[ERROR] /***/spring-cloud-function/spring-cloud-function-context/src/main/kotlin/org/springframework/cloud/function/context/config/TypeUtils.kt:[89,1] Conflicting overloads: internal fun getContinuationTypeArguments(type: Type): Type defined in org.springframework.cloud.function.context.config in file TypeUtils.kt, private fun getContinuationTypeArguments(type: Type): Type defined in org.springframework.cloud.function.context.config
. . .

am i missing something?

[apoupard]

Very strange
I can reproduce a similar error just by using @file:JvmName("TypeUtils2") instead of @file:JvmName("TypeUtils") in the file src/main/kotlin/org/springframework/cloud/function/context/config/TypeUtils.kt.

What command are you using to do a full build? ./mvnw clean package?

Can you try manually removing the ./spring-cloud-function-context/target directory?
rm -fr ./spring-cloud-function-context/target

[apoupard]

I’ve checked — most of the Kotlin utility functions I added can be implemented in Java, so I’ll migrate them.

[apoupard]

@olegz I have moved most of the Kotlin utility methods into KotlinUtils.java. I expect this will solve your problem. Let me know if you still encounter any issues.

I also tried to resolve the DCO issue by running:
As written in the documentation, I have done:

git rebase HEAD~6 --signoff

Then I force-pushed the changes using:

git push --force-with-lease origin feat/kotlin-support-enhancement

I verified that all commits now include the line:

Signed-off-by: Adrien Poupard <[email protected]>

However, the DCO check is still failing. Do you have any idea why this might be happening?