https://build.spring.io/browse/INTSAMPLES-NIGHTLY-1898/
There is no guarantee that if `File.exists()`, the real write to file has occurred
* Add `while()` to check not only `File.exists()` but also its `length()` only after that proceed to assert logic
Since we provide a custom `FileNameGenerator` via `fileNameExpression` we should ensure somehow `BeanFactory` injection to that
`FileWritingMessageHandlerSpec` is a `FactoryBean` since version DSL `1.2` and a particular `BPP` takes care about `Spec` internals and register custom `FileNameGenerator` as a bean.
Use standard `FactoryBean` injection in the `lines()` flow to populate the target `FileWritingMessageHandler` to the flow
Generate pom for all project to apply SI Java DSL 1.2 GA
Fixes GH-180 (https://github.com/spring-projects/spring-integration-samples/issues/180)
* Apply `PollerSpec.errorChannel(String)` style
* Replace `fileNameExpression()` to `fileNameGenerator()` to avoid `No BeanFactory` for `EvaluationContext`
* Use `.trigger()` instead of `.handle()` for `FileWritingMessageHandler.trigger()`
* Fix race condition in test, when file exists already, but there is no content yet
JIRA: https://jira.spring.io/browse/INTSAMPLES-149
Polishing - PR Comments
Polishing - Work Around DSL Issue #119
Make test compatible with Windows.
Also reset Application context `DirtiesContext.ClassMode.AFTER_EACH_TEST_METHOD`.
Since tests uses the same target resources we should be sure that they use clear foundation before running
