DATAGRAPH-1359 - Run Checkstyle in verify phase.

Checkstyle is configured to run in the validation phase in spring-data-parent, spring-data-neo4j used to use validate as well. Also, spring-data-neo4j has checkstyle configured to check the test sources as well. The later is done in test-compile.

So checkstyle was executed indeed twice during validation, once for the sources and once for the test-compile.

This commit changes spring-data-neo4j’s configuration to run in verify, after tests ran. This makes checkstyle only run once.

For a quick look if all sources are correct, one can use ` ./mvnw checkstyle:check@verify` before running a full blown `./mvnw verify`. While the Java compiler now can flag invalid code immediate, checkstyle will discover the rest only afterwards.

While working on this a flaw in the combine.self="override" attribute was discovered: It works of course only for the maven configurational attributes, not for the checkstyle rules themselve. Therefor the `io.spring.nohttp.checkstyle.check.NoHttpCheck` has been added to the local configuration as well.

In the process of the bug fix, the sort pom plugin has been applied with the configuration as already available.

Author: michael-simons

etc/checkstyle/config.xml

@@ -23,6 +23,11 @@
     <module name="NewlineAtEndOfFile"/>
     <module name="SuppressWarningsFilter" />
 
+    <module name="io.spring.nohttp.checkstyle.check.NoHttpCheck">
+        <!-- XML requires double escaping, config gets XML-processed twice -->
+        <property name="allowlist" value="http://www\.querydsl\.com.*&amp;#10;http://www\.prowaveconsulting\.com.*&amp;#10;http://www\.scispike\.com.*&amp;#10;http://.*.icu-project\.org.*" />
+    </module>
+
     <module name="com.puppycrawl.tools.checkstyle.TreeWalker">
         <module name="SuppressWarningsHolder" />