This is a compiler warning, not an IDE warning ("javac -Xlint:all" - additional checks introduced in JDK7, but still valid in prior versions of the JDK).  I get them passed through in Eclipse as well though.  Row is only explicit about its usage in the regard that the Generic class must extend RowKey.  You need to use "Row<?>" to remove the compiler warning. The "extends RowKey" is extraneous.  Do you want me to remove "extends RowKey"?