Merge pull request #3431 from jglick/flatten

[JENKINS-51247] Simplified usage of flatten-maven-plugin

.gitignore

 target
-.flattened-pom.xml
 work
 
 # IntelliJ project files 

.mvn/extensions.xml

@@ -2,6 +2,6 @@
   <extension>
     <groupId>io.jenkins.tools.incrementals</groupId>
     <artifactId>git-changelist-maven-extension</artifactId>
-    <version>1.0-beta-2</version>
+    <version>1.0-beta-3</version>
   </extension>
 </extensions>

pom.xml

@@ -28,7 +28,7 @@ THE SOFTWARE.
   <parent>
     <groupId>org.jenkins-ci</groupId>
     <artifactId>jenkins</artifactId>
-    <version>1.44</version>
+    <version>1.45</version>
     <relativePath />
   </parent>
 
@@ -114,7 +114,7 @@ THE SOFTWARE.
     <!-- TODO: JENKINS-36716 - Switch to Medium once FindBugs is cleaned up, 430 issues on Mar 10, 2018 -->
     <findbugs.effort>Max</findbugs.effort>
     <findbugs.threshold>High</findbugs.threshold>
-    <findbugs.excludeFilterFile>../src/findbugs/findbugs-excludes.xml</findbugs.excludeFilterFile>
+    <findbugs.excludeFilterFile>${project.basedir}/../src/findbugs/findbugs-excludes.xml</findbugs.excludeFilterFile>
   </properties>
 
   <!-- Note that the 'repositories' and 'pluginRepositories' blocks below are actually copy-pasted