prepare 5.12.0 release - Githubissues

[5.12.0] - 2020-04-03

New configuration option streamInitialReconnectDelayMillis allows setting the initial delay (not including jitter) for stream reconnections.

The stream reconnection behavior has been changed to be consistent with other LaunchDarkly SDKs, as follows:

Previously, there was a fixed delay of 125 milliseconds for the first attempt to reconnect after a stream failure, which would then increase with an exponential backoff for subsbequent retries up to a maximum of 15 seconds (but the backoff was used only after HTTP error responses, not connection failures).
Now, the delay starts at 1000 milliseconds, unless changed with streamInitialReconnectDelayMillis.
The new maximum is 30 seconds.
The backoff now applies to all types of stream failures.
There is now a jitter that randomly reduces each delay by up to 50%.
The delay now resets to the initial level if the stream has been active for at least 60 seconds.