Hi, I've recently started to evaluate Flink and have found it odd that its Tuple types, while Serializable, don't implement java.lang.Comparable.This means that I either need to provide an KeySelector for many operations or subtype the Tuple types and provide my own implementation of compareTo for each. Is there a technical reason why this was omitted? For example, the JOOQ/JOOL Tuple types all implement Comparable:https://github.com/jOOQ/jOOL/blob/master/jOOL-java-8/src/main/java/org/jooq/lambda/tuple/Tuple2.java#L39 As an aside, I tried replacing usage of Flink's Tuple types with the JOOL ones but they caused a StackOverflowError similar to this one:https://issues.apache.org/jira/browse/FLINK-3922
Thanks, Frank Grimes
