Fix #section-buffer by replacing .withAttributes by .addAttributes to avoid overwriting the .async option.
* Update StreamBuffersRateDocTest.java
Fix #section-buffer by replacing .withAttributes by .addAttributes to avoid overwriting the .async option.
* Re enabling Java tests in akka-docs (they were not run before)
* Fixed bug #19764
* #19735 Rewrote every sample using the deprecated PushPullStage and friends
using GraphStage
* Pruned old unused graph images
* Added missing graffle file for new graph images