Update Changelog for release of version 4.0.0

Author: LaunchDarklyCI

CHANGELOG.md

@@ -3,6 +3,20 @@
 
 All notable changes to the LaunchDarkly Java SDK will be documented in this file. This project adheres to [Semantic Versioning](http://semver.org).
 
+## [4.0.0] - 2018-05-10
+
+### Changed:
+- To reduce the network bandwidth used for analytics events, feature request events are now sent as counters rather than individual events, and user details are now sent only at intervals rather than in each event. These behaviors can be modified through the LaunchDarkly UI and with the new configuration option `inlineUsersInEvents`. For more details, see [Analytics Data Stream Reference](https://docs.launchdarkly.com/v2.0/docs/analytics-data-stream-reference).
+- When sending analytics events, if there is a connection error or an HTTP 5xx response, the client will try to send the events again one more time after a one-second delay.
+- The `LdClient` class is now `final`.
+
+### Added:
+- New methods on `LDConfig.Builder` (`updateProcessorFactory`, `featureStoreFactory`, `eventProcessorFactory`) allow you to specify different implementations of each of the main client subcomponents (receiving feature state, storing feature state, and sending analytics events) for testing or for any other purpose. The `Components` class provides factories for all built-in implementations of these.
+
+### Deprecated:
+- The `featureStore` configuration method is deprecated, replaced by the new factory-based mechanism described above.
+
+
 ## [3.0.3] - 2018-03-26
 ### Fixed
 * In the Redis feature store, fixed a synchronization problem that could cause a feature flag update to be missed if several of them happened in rapid succession.