title: Apache Ignite generated key for cluster but no key class
body: <p>I used Ignite Web Console to generate a cluster configuration for an existing database.  One of the tables in question has no key--it consists of two columns, both integers, neither of which is a key.  There is a foreign key constraint that one of the columns must exist in another table, but I don't especially care about that.</p>
  
  <p>In the generated cluster xml, each of the two columns is represented as a value field.  These two fields match up with the generated POJO class as well.  However, in the "keyType" field of the cluster config, it references a generated key class that, as far as I can tell, does not exist.  If the POJO class for the table is Foo, then the key class is written down as FooKey, but this class does not exist in the project, and there is no definition for what fields would be in the key.</p>
  
  <p>What am I supposed to do when referencing this cache?  Do I need to create an implementation of this key class myself?  When I make calls to the cache, does it need to be in the Entry format?  How does the key-value store work when there is no key in the original table?</p>