pom: filter out naming related Spotbugs issues

Motivation:
As nfs4j uses autogenerated code, filter out naming issues to
make critical problems more visible.

Modification:
introduce spotbugs-exclude.xml file containing warnings that
should be ignored.

Result:
critical problems more visible

Acked-by: Paul Millar
Acked-by: Lea Morschel
Target: master

pom.xml

@@ -85,6 +85,9 @@
             <groupId>com.github.spotbugs</groupId>
             <artifactId>spotbugs-maven-plugin</artifactId>
             <version>3.1.12</version>
+            <configuration>
+               <excludeFilterFile>${maven.multiModuleProjectDirectory}/spotbugs-exclude.xml</excludeFilterFile>
+            </configuration>
         </plugin>
         <plugin>
             <groupId>org.jacoco</groupId>

spotbugs-exclude.xml

+<?xml version="1.0" encoding="UTF-8"?>
+<FindBugsFilter
+              xmlns="https://github.com/spotbugs/filter/3.0.0"
+              xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+              xsi:schemaLocation="https://github.com/spotbugs/filter/3.0.0
+                  https://raw.githubusercontent.com/spotbugs/spotbugs/3.1.0/spotbugs/etc/findbugsfilter.xsd">
+
+  <!-- ignore auto-generated code -->
+  <Match>
+    <Class name="~org\.dcache\.nfs\.v\d\.xdr\..*" />
+    <Or>
+      <Bug pattern="NM_CLASS_NAMING_CONVENTION" />
+      <Bug pattern="NM_METHOD_NAMING_CONVENTION" />
+    </Or>
+  </Match>
+
+</FindBugsFilter>