[FLINK-20318][Connector/kafka]Fix cast question for properies() method in kafka ConnectorDescriptor

[hehuiyuan]

What is the purpose of the change

This pull resquest fixes Kafka connector. There is a cast problem when use properties method.

  Properties props = new Properties();
   props.put( "enable.auto.commit", "false");
   props.put( "fetch.max.wait.ms", "3000");
   props.put("flink.poll-timeout", 5000);
   props.put( "flink.partition-discovery.interval-millis", false);

  kafka = new Kafka()
       .version("0.11")
       .topic(topic)
       .properties(props);

Exception in thread "main" java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.String

Exception in thread "main" java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String

Brief change log

• change (String) v ----> String.valueOf() in Kafka.java

Documentation

• Does this pull request introduce a new feature? ( no)

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Last check on commit ce2ae5e (Sat Aug 28 12:16:38 UTC 2021)

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[hehuiyuan]

Hi @JingsongLi , who can help look at this problem?

[luoyuxia]

@hehuiyuan
Thank you for your contribution.
Would you like to add tests to cover this change?
I think you can modify KafkaTest directly:
change

properties.put("zookeeper.stuff", "12"); properties.put("kafka.stuff", "42");

->
properties.put("zookeeper.stuff", "12"); properties.put("kafka.stuff", 42);

so that we can ensure your code change works.

[hehuiyuan]

@hehuiyuan
Thank you for your contribution.
Would you like to add tests to cover this change?
I think you can modify KafkaTest directly:
change

properties.put("zookeeper.stuff", "12"); properties.put("kafka.stuff", "42");

->
properties.put("zookeeper.stuff", "12"); properties.put("kafka.stuff", 42);

so that we can ensure your code change works.

ok.

[hehuiyuan]

HI @luoyuxia , done.

[JingsongLi]

Looks good to me, thank @hehuiyuan