Bump com.github.spotbugs from 5.2.5 to 6.0.7 (#991)

Author: dependabot[bot]

build.gradle

@@ -5,7 +5,7 @@ plugins {
   id 'signing'
   id 'pmd' // code check, working on source code
   id 'com.diffplug.spotless' version '6.25.0' //code format
-  id 'com.github.spotbugs' version '5.2.5' // code check, working on byte code
+  id 'com.github.spotbugs' version '6.0.7' // code check, working on byte code
   id 'de.undercouch.download' version '5.5.0'
   id 'kr.motd.sphinx' version '2.10.1' // documentation generation
   id 'jacoco' // java code coverage plugin

gradle/scripts/spotbugs.gradle

@@ -1,21 +1,26 @@
 // spotBugs is a code check tool, working on byte code
 
+// workaround because imports do not work in files that are only included by build.gradle
+def classLoader = plugins['com.github.spotbugs'].class.classLoader
+def SpotBugsEffort = classLoader.findLoadedClass( 'com.github.spotbugs.snom.Effort' )
+def SpotBugsConfidence = classLoader.findLoadedClass( 'com.github.spotbugs.snom.Confidence' )
+
 spotbugs{
   ignoreFailures = true // dont let the build fail on rule violations
-  effort = 'max'
-  reportLevel = 'high'
+  effort = SpotBugsEffort.valueOf("MAX")
+  reportLevel = SpotBugsConfidence.valueOf("HIGH")
 }
 
 spotbugsMain{
   reports{
-    html.enabled = false
-    xml.enabled = true
+    html.required.set(false)
+    xml.required.set(true)
   }
 }
 
 spotbugsTest{
   reports{
-    html.enabled = false
-    xml.enabled = true
+    html.required.set(false)
+    xml.required.set(true)
   }
 }