#3591 Potential fix for duplicate methods generated.

[Hypnagokali]

Potential fix for: #3591

I am not sure if my solution is an acceptable one, but it solves this bug for now.
Problem: There were two methods generated and both are written to the mapper class because the selectionParameters in the ContainerMappingMethods are not equal and therefore the methods are not equal and finally both are used.

• The defined mapping has an empty instance of SelectionParameters (returned from MappingOptions)
• The generated mapping has null for selectionParameters.

Solution: MappingOption now returns null for selectionParameters if no values have been set.

I am still confused why two methods of beanListToBeanDtoList are forged at all. I would like to take another look at this.

[zyberzebra]

I am not sure if my solution is an acceptable one, but it solves this bug for now. Problem: There were two methods generated and both are written to the mapper class because the selectionParameters in the ContainerMappingMethods are not equal and therefore the methods are not equal and finally both are used.

Good Catch, the question is now what leads to this behaviour? And is your provided solution just a workaround/bandaid for the actual problem. But I tried your solution and it works.
I'm also gonna try and have look what causes this.

Maybe it's something caused by the recursive nature here?
Bean#Beans#Bean#Beans#......
And maybe it would generate even more duplicate methods, but it stops before that because of the first duplicate error

[Hypnagokali]

Maybe it's something caused by the recursive nature here? Bean#Beans#Bean#Beans#...... And maybe it would generate even more duplicate methods, but it stops before that because of the first duplicate error

Thanks for the feedback. Yes, the recursive structure of the bean must be the cause, but the MapperCreationProcess ends "successfully" and the duplication error only becomes visible during compilation. At some point, the mapper decides not to create any more methods although the equals method fails.

Edited:
Okay, I may have found the root cause:
In the method PropertyMapping.PropertyMappingBuilder#forge() an IterableMapping is forged, but never inserted into or retrieved from the map MappingBuilderContext#getForgedMethodsUnderCreation(). With this change it seems to work as expected and only one beanListToBeanDtoList method is forged.
I still have to look at the other assignments in the PropertyMappingBuilder#forge().

[Hypnagokali]

Edited:

I have added a test for StreamMapping and MapMapping.
It works, but actually both mapping methods are generated twice. However, finally only one method is added to MappingBuilderContext#mappingsToGenerate
Sorry, I have totally missed something. There are actually two methods added for StreamMapping, but it does not lead to a compilation error, because the second method is suffixed with 1: containerBeanStreamToContainerBeanDtoStream1
I will fix this quickly. And I will rewrite the test using GeneratedSource

[Hypnagokali]

Okay, everything should be done now. I hope I haven't missed anything.

I still have a question:
All workflow jobs fail with: "Some files do not have the expected license header", what does that mean?

[thunderhook]

Okay, everything should be done now. I hope I haven't missed anything.

I still have a question: All workflow jobs fail with: "Some files do not have the expected license header", what does that mean?

This is a check if every file contains the copyright header at the beginning of a file.

/*
 * Copyright MapStruct Authors.
 *
 * Licensed under the Apache License version 2.0, available at http://www.apache.org/licenses/LICENSE-2.0
 */

[zyberzebra]

Maybe a new factory method would be better than using the null as parameter? Just a thought, my architecture knowledge for mapstruct is not big enough

[Hypnagokali]

You are right - it could be confusing. I have changed that to SelectionParameters.emptyInstance()

[zyberzebra]

It's working! Pretty cool! :) Lets see what the maintainers have to say

[zyberzebra]

Is this Issue related? #3532