fixed NPE from new global config

Note, that I'm not sure if it is fix or workaround.
Not, that it misbehaved for me completly - the items added in config
could not be removed in  2.434(.1) STS jenkins
renamed settings to jtreg as it should be

report-jtreg/src/main/java/io/jenkins/plugins/report/jtreg/JenkinsReportJckGlobalConfig.java

@@ -7,6 +7,7 @@
 import org.kohsuke.stapler.DataBoundSetter;
 import org.kohsuke.stapler.StaplerRequest;
 
+import java.util.ArrayList;
 import java.util.List;
 import java.util.logging.Logger;
 
@@ -18,8 +19,8 @@ public class JenkinsReportJckGlobalConfig extends GlobalConfiguration {
     private static Logger logger = Logger.getLogger(JenkinsReportJckGlobalConfig.class.getName());
 
     String diffToolUrl;
-    List<ComparatorLinksGroup> comparatorLinksGroups;
-    List<ConfigItem> configItems;
+    List<ComparatorLinksGroup> comparatorLinksGroups = new ArrayList<>();
+    List<ConfigItem> configItems = new ArrayList<>();
 
     public static JenkinsReportJckGlobalConfig getInstance() {
         return GlobalConfiguration.all().get(JenkinsReportJckGlobalConfig.class);

report-jtreg/src/main/resources/io/jenkins/plugins/report/jtreg/JenkinsReportJckGlobalConfig/config.jelly

@@ -1,6 +1,6 @@
 <?jelly escape-by-default='true'?>
 <j:jelly xmlns:j="jelly:core" xmlns:f="/lib/form">
-    <f:section title="Jenkins Report Jck Plugin">
+    <f:section title="Jenkins Report Jtreg Plugin">
         <f:entry title="Diff-tool url (eg http://server.my:9090)" field="diffToolUrl">
             <f:textbox/>
         </f:entry>