[jira] [Updated] (KAFKA-16858) Flatten SMT throws NPE

["Adam Strickland (Jira)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/KAFKA-16858?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Adam Strickland updated KAFKA-16858:
------------------------------------
    Attachment: proto.proto

> Flatten SMT throws NPE
> ----------------------
>
>                 Key: KAFKA-16858
>                 URL: https://issues.apache.org/jira/browse/KAFKA-16858
>             Project: Kafka
>          Issue Type: Bug
>          Components: connect
>    Affects Versions: 3.6.0
>         Environment: Kafka 3.6 by way of CP 7.6.0
>            Reporter: Adam Strickland
>            Priority: Major
>         Attachments: FlattenTest.java, proto.proto
>
>
> {{ConnectSchema.expectedClassesFor}} sometimes will throw an NPE as part of a call to an SMT chain.  Stack trace snippet:
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.apply(MomentFlatten.java:84)}}
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.applyWithSchema(MomentFlatten.java:173)}}
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.buildWithSchema(MomentFlatten.java:280)}}
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.buildWithSchema(MomentFlatten.java:280)}}
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.buildWithSchema(MomentFlatten.java:280)}}
> {{at com.github.momenttechnology.kafka.connect.transforms.MomentFlatten.buildWithSchema(MomentFlatten.java:274)}}
> {{at org.apache.kafka.connect.data.Struct.put(Struct.java:203)}}
> {{at org.apache.kafka.connect.data.Struct.put(Struct.java:216)}}
> {{at org.apache.kafka.connect.data.ConnectSchema.validateValue(ConnectSchema.java:255)}}
> {{at org.apache.kafka.connect.data.ConnectSchema.validateValue(ConnectSchema.java:213)}}
> {{at org.apache.kafka.connect.data.ConnectSchema.validateValue(ConnectSchema.java:224)}}
> {{at org.apache.kafka.connect.data.ConnectSchema.expectedClassesFor(ConnectSchema.java:268)}}
> (the above transform is a sub-class of {{{}o.a.k.connect.transforms.Flatten{}}}; have confirmed that the error occurs regardless).
> The field being transformed is an array of structs. If the call to {{Schema#valueSchema()}} (o.a.k.connect.data.ConnectSchema.java:255) returns {{{}null{}}}, the subsequent call to {{Schema#name()}} at o.a.k.connect.data.ConnectSchema:268 throws an NPE.
> The strange thing that we have observed is that this doesn't always happen; *sometimes* the struct's schema is found and sometimes it is not. We have been unable to determine the root cause, but have constructed a test that replicates the problem as observed (see attachment).
> In our case we have worked around the issue with the aforementioned sub-class of {{{}Flatten{}}}, catching and logging the NPE on that specific use-case.



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