Add Java 21 to GitHub testing matrix (#140)

* Add Java 21 to GitHub testing matrix

* Update Spotbugs and Jacoco.

.github/workflows/maven.yml

@@ -22,7 +22,7 @@ jobs:
 
     strategy:
       matrix:
-        java: [ 11, 17 ]
+        java: [ 11, 17, 21 ]
 
     name: Java ${{ matrix.java }}
 

pom.xml

@@ -42,7 +42,7 @@
 
     <properties>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-        <spotbugs.version>4.6.0</spotbugs.version>
+        <spotbugs.version>4.8.6</spotbugs.version>
         <org.junit.version>5.10.0</org.junit.version>
         <java.version>11</java.version>
         <kotlin.version>1.9.10</kotlin.version>
@@ -336,7 +336,7 @@
             <plugin>
                 <groupId>com.github.spotbugs</groupId>
                 <artifactId>spotbugs-maven-plugin</artifactId>
-                <version>4.7.0.0</version>
+                <version>4.8.6.6</version>
                 <configuration>
                     <excludeFilterFile>spotbugs-exclude.xml</excludeFilterFile>
                     <includeTests>true</includeTests>
@@ -397,7 +397,7 @@
                     <plugin>
                         <groupId>org.jacoco</groupId>
                         <artifactId>jacoco-maven-plugin</artifactId>
-                        <version>0.8.8</version>
+                        <version>0.8.12</version>
                         <executions>
                             <execution>
                                 <goals>

spotbugs-exclude.xml

@@ -22,7 +22,12 @@
   <Bug pattern="SE_BAD_FIELD_STORE"/>
 </Match>
 
-<Match>
+  <Match>
+    <!-- We throw from constructors on illegal arguments, i.e. programming errors. -->
+    <Bug pattern="CT_CONSTRUCTOR_THROW"/>
+  </Match>
+
+  <Match>
   <!-- This seems to get triggered by certain kotlin constructs though they look safe -->
   <Bug pattern="BC_BAD_CAST_TO_ABSTRACT_COLLECTION"/>
   <Source name="~.*\.kt" />