Polish: map entries should be iterated when both the key and value are needed

[igor-suhorukov]

use java 8 language features to iterate on maps and transform data set by streams

[jhoeller]

Inspired by this PR, I've taken a broad sweep over existing Map.Entry iteration cases as well: https://jira.spring.io/browse/SPR-16646, rolling your changes into it in a slightly revised fashion.

Once again, thanks for your efforts there!

[igor-suhorukov]

@jhoeller thank you for your great work!
Could you please talk two words about Russian community contribution and my PRs on JPoint conference Moscow?

Regards,
Igor

[jhoeller]

Absolutely, my JPoint keynote is about Spring Framework 5 and our JDK 8/9 specific work, and many of your contributions were related to Java 8+ API usage... a fine example for how community contributions make our ongoing theme much more complete that we initially shipped it, and how those contributions provide direct triggers for follow-up work on our side. It'll be my pleasure to explicitly mention your PRs!

[sbrannen]

@igor-suhorukov, you're like a... PR machine! 👏

[igor-suhorukov]

@jhoeller thanks a lot for your time because of sometimes my pull requests are too noisy)))
I am waiting for your keynote in Moscow!

[igor-suhorukov]

@sbrannen thanks) to be continued...