Console strips unknown properties on /validate connectors call

[tomasz-sadura]

Use the following config for a connector (PostgreSQL Debezium):

{
    "connector.class": "io.debezium.connector.postgresql.PostgresConnector",
    "topic.prefix": "p1",
    "database.hostname": "xxx.eu-west-1.rds.amazonaws.com",
    "database.user": "postgres",
    "database.password": "xxx",
    "database.dbname": "postgres",
    "database.sslmode": "disable",
    "plugin.name": "pgoutput",
    "key.converter": "org.apache.kafka.connect.json.JsonConverter",
    "value.converter": "org.apache.kafka.connect.json.JsonConverter",
    "header.converter": "org.apache.kafka.connect.storage.SimpleHeaderConverter",
    "name": "debezium-postgresql-connector-1",
    "converters": "someConverter",
    "someConverter.type": "com.some.converter.debezium.SomeConverter",
    "someConverter.tables": "public.test_table",
    "someConverter.tables.public.test_table.columns": "tags,schedule"
}

The properties someConverter.* are dynamic based on the converters value. These properties are not send to Kafka Connect with the /validate call, causing the connector to be unable to valiidate the config, as the required converter properties (someConverter.type) are not given. The UI hangs and user cannot create the connector.

Expected behaviour:
All of the defined properties are sent with the /valdiate call.

[tomasz-sadura]