#496 Pipeline pattern (#967)

* #496 Add pipeline module to parent pom ✨

* #496: Add main application class and test for pipeline

* #496: Checkstyle format and add log messages on pipeline stages 🎨

* #496: Fill readme sections of pipeline ✨

* #496: Javadocs and checkstyle formatting 🎨

* #496: Follow PMD checks and add more explanation as block comment on App.java

* #496: Apply requested PR changes by iluwatar 🎨

pipeline/README.md

@@ -0,0 +1,37 @@
+---
+layout: pattern
+title: Pipeline
+folder: pipeline
+permalink: /patterns/pipeline/
+categories: Behavioral
+tags:
+ - Java
+ - Functional
+ - Difficulty-Intermediate
+---
+
+## Intent
+Allows processing of data in a series of stages by giving in an initial input and passing the processed output to be used by the next stages.
+
+## Applicability
+Use the Pipeline pattern when you want to
+
+* execute individual stages that yields a final value
+* add readability to complex sequence of operations by providing a fluent builder as an interface
+* improve testability of code since stages will most likely be doing a single thing, complying to the [Single Responsibility Principle (SRP)](https://java-design-patterns.com/principles/#single-responsibility-principle)
+
+## Typical Use Case
+
+* implement stages and execute them in an ordered manner
+
+## Real world examples
+
+* [java.util.Stream](https://docs.oracle.com/javase/8/docs/api/java/util/stream/package-summary.html)
+* [Maven Build Lifecycle](http://maven.apache.org/guides/introduction/introduction-to-the-lifecycle.html)
+* [Functional Java](https://github.com/functionaljava/functionaljava)
+
+## Credits
+
+* [The Pipeline Pattern — for fun and profit](https://medium.com/@aaronweatherall/the-pipeline-pattern-for-fun-and-profit-9b5f43a98130)
+* [The Pipeline design pattern (in Java)](https://medium.com/@deepakbapat/the-pipeline-design-pattern-in-java-831d9ce2fe21)
+* [Pipelines | Microsoft Docs](https://docs.microsoft.com/en-us/previous-versions/msp-n-p/ff963548(v=pandp.10))