!str #16448 Change error to failure

* one API change OverflowStrategy.error -> OverflowStrategy.fail
* error is still kept in the internals where we are at the reactive
  streams level

akka-docs-dev/rst/java/stream-graphs.rst

@@ -184,7 +184,7 @@ If we run this example we see that
 
 This example highlights that one solution to avoid deadlocks in the presence of potentially unbalanced cycles
 (cycles where the number of circulating elements are unbounded) is to drop elements. An alternative would be to
-define a larger buffer with ``OverflowStrategy.error`` which would fail the stream instead of deadlocking it after
+define a larger buffer with ``OverflowStrategy.fail`` which would fail the stream instead of deadlocking it after
 all buffer space has been consumed.
 
 As we discovered in the previous examples, the core problem was the unbalanced nature of the feedback loop. We

akka-docs-dev/rst/java/stream-quickstart.rst

@@ -120,7 +120,7 @@ elements*" this can be expressed using the ``buffer`` element:
 
 The ``buffer`` element takes an explicit and required ``OverflowStrategy``, which defines how the buffer should react
 when it receives another element element while it is full. Strategies provided include dropping the oldest element (``dropHead``),
-dropping the entire buffer, signalling errors etc. Be sure to pick and choose the strategy that fits your use case best.
+dropping the entire buffer, signalling failures etc. Be sure to pick and choose the strategy that fits your use case best.
 
 Materialized values
 -------------------