[RELEASE] Java driver 4.6.1

[Olivier Michallat]

We've just released version 4.6.1 of the driver. It addresses the performance issue described last week.

We've optimized the internal write coalescer to use less I/O event loop cycles (it used to reschedule itself a few times before shutting down in order to stay busy, but that turned out to be unnecessary because every incoming request will schedule a run if necessary). With those changes, the two scenarios that exhibited a degradation are back to 4.4.0 levels.

As a reminder, we haven't seen any evidence of the issue outside of those specific scenarios: when requests are executed from multiple client threads, we observe similar performance for 4.4.0, 4.6.0 and 4.6.1. Yet we still recommend that 4.5/4.6 users upgrade to 4.6.1 as a precautionary measure. 

Here is the changelog:

### 4.6.1

- [bug] JAVA-2676: Don't reschedule write coalescer after empty runs

As usual, the driver is available from Maven central:

<dependency>

  <groupId>com.datastax.oss</groupId>

  <artifactId>java-driver-core</artifactId>

  <version>4.6.1</version>

</dependency>

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The Java driver team