Kafka connect: The configuration XXX was supplied but isn't a known config in AdminClientConfig

Question

When starting Kafka-Connect, I saw lots of warnings

10:33:56.706 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'config.storage.topic' was supplied but isn't a known config.
10:33:56.707 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'group.id' was supplied but isn't a known config.
10:33:56.708 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'status.storage.topic' was supplied but isn't a known config.
10:33:56.709 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'internal.key.converter.schemas.enable' was supplied but isn't a known config.
10:33:56.710 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'config.storage.replication.factor' was supplied but isn't a known config.
10:33:56.710 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'offset.flush.interval.ms' was supplied but isn't a known config.
10:33:56.711 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'key.converter.schemas.enable' was supplied but isn't a known config.
10:33:56.712 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'internal.key.converter' was supplied but isn't a known config.
10:33:56.712 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'internal.value.converter.schemas.enable' was supplied but isn't a known config.
10:33:56.713 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'status.storage.replication.factor' was supplied but isn't a known config.
10:33:56.713 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'value.converter.schemas.enable' was supplied but isn't a known config.
10:33:56.714 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'internal.value.converter' was supplied but isn't a known config.
10:33:56.714 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'offset.storage.replication.factor' was supplied but isn't a known config.
10:33:56.715 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'offset.storage.topic' was supplied but isn't a known config.
10:33:56.715 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'value.converter' was supplied but isn't a known config.
10:33:56.716 [DistributedHerder] WARN  org.apache.kafka.clients.admin.AdminClientConfig - The configuration 'key.converter' was supplied but isn't a known config.

Some post says its because topic creation is disabled, but it's not in my case. The storage topic is still created.

The other mentions it's version mismatch, it's also not in my case. The kafka broker version is 1.0.0, and Kafka-Connect the same as the following pom.xml. Those configurations are provided during the start of Kafka-Connect

<properties>
      <!-->
      Confluent version must match Kafka version
      https://docs.confluent.io/current/installation/versions-interoperability.html
      <-->
        <kafka.version>1.0.0</kafka.version>
        <confluent.version>5.1.2</confluent.version>
        <debezium-connector-mongodb.version>0.7.4</debezium-connector-mongodb.version>
        <logging.version>2.11.2</logging.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>connect-json</artifactId>
            <version>${kafka.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>connect-runtime</artifactId>
            <version>${kafka.version}</version>
            <scope>runtime</scope>
            <exclusions>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>
        <dependency>
            <groupId>io.debezium</groupId>
            <artifactId>debezium-connector-mongodb</artifactId>
            <version>${debezium-connector-mongodb.version}</version>
        </dependency>
        <dependency>
            <groupId>org.apache.kafka</groupId>
            <artifactId>connect-file</artifactId>
            <version>${kafka.version}</version>
            <scope>runtime</scope>
        </dependency>
        <dependency>
            <groupId>io.confluent</groupId>
            <artifactId>kafka-connect-jdbc</artifactId>
            <version>${confluent.version}</version>
            <scope>runtime</scope>
            <exclusions>
                <exclusion>
                    <groupId>log4j</groupId>
                    <artifactId>log4j</artifactId>
                </exclusion>
                <exclusion>
                    <groupId>org.slf4j</groupId>
                    <artifactId>slf4j-log4j12</artifactId>
                </exclusion>
            </exclusions>
        </dependency>

what would be something else I should check for fixing those warnings? I can see the data is delivered via Kafka-Connect, but still am worried about theses warnings

Answer 1

These are just WARNings, and can be ignored. In future releases they will be correctly suppressed: https://github.com/apache/kafka/pull/5876