[jira] [Created] (KAFKA-8297) Kafka Streams ConsumerRecordFactory yields difficult compiler error about generics

["Michael Drogalis (JIRA)" <ji...@apache.org>]

Michael Drogalis created KAFKA-8297:
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             Summary: Kafka Streams ConsumerRecordFactory yields difficult compiler error about generics
                 Key: KAFKA-8297
                 URL: https://issues.apache.org/jira/browse/KAFKA-8297
             Project: Kafka
          Issue Type: Bug
          Components: streams
            Reporter: Michael Drogalis


When using the ConsumerRecordFactory, it's convenient to specify a default topic to create records with:

{code:java}
ConsumerRecordFactory<String, User> inputFactory = new ConsumerRecordFactory<>(inputTopic, keySerializer, valueSerializer);
{code}

However, when the factory is used to create a record with a String key:

{code:java}
inputFactory.create("any string", user)
{code}

Compilation fails with the following warning:

{code:java}
Ambiguous method call. Both:

create(String, User) in ConsumerRecordFactory and
create(String, User) in ConsumerRecordFactory match
{code}

At first glance, this is a really confusing error to see during compilation. What's happening is that there are two clashing signatures for `create`: create(K, V) and create(String, V). The latter signature represents a topic name.

It seems like fixing this would require breaking the existing interface. This is a really opaque problem to hit though, and it would be great if we could avoid having users encounter this.



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