Minor Description
In `org.apache.spark.streaming.kinesis` there's a Java interface `KinesisInitialPosition` - for some reason it's not public, so can't be used.
The reason it needs to be used is simple: it is the parent of `KinesisInitialPositions.Latest` and `KinesisInitialPositions.TrimHorizon`. Without using it, it's impossible to pass instances of `Latest` and `TrimHorizon` around without calling them by name.
The workaround is to use the enum `InitialPositionInStream` instead, and a factory method `fromKinesisInitialPosition(..)` - but it doesn't seem like the correct pattern, because it belongs to Amazon Kinesis Client library and not Spark (it's currently the only import in my class which is outside of `org.apache.spark`).
The change is trivial, so it's mainly a matter of why not to do it.
KinesisInitialPositions: https://github.com/apache/spark/blob/master/external/kinesis-asl/src/main/java/org/apache/spark/streaming/kinesis/KinesisInitialPositions.java
KinesisInitialPosition: https://github.com/awslabs/amazon-kinesis-client/blob/master/amazon-kinesis-client/src/main/java/software/amazon/kinesis/common/InitialPositionInStream.java
